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Schemas for Material Properties

We present throughout this page a list of JSON schemas and example representations concerning properties. The reader is referred to their respective documentation pages, accessible by clicking the headers below, for a review of their underlying physical significance.

Scalar Properties

Total Energy

Total energy contains the total energy of the unit cell.

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{
    "schemaId": "properties-directory-scalar-total-energy", 
    "allOf": [
        {
            "required": [
                "name", 
                "units"
            ], 
            "schemaId": "core-reusable-energy", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ], 
            "properties": {
                "units": {
                    "anyOf": [
                        {
                            "enum": [
                                "kJ/mol", 
                                "eV", 
                                "J/mol", 
                                "hartree", 
                                "cm-1", 
                                "rydberg", 
                                "eV/atom"
                            ]
                        }, 
                        {
                            "enum": [
                                "eV/A^2"
                            ]
                        }
                    ]
                }, 
                "name": {
                    "type": "string"
                }
            }, 
            "title": "energy schema"
        }
    ], 
    "properties": {
        "name": {
            "enum": [
                "total_energy"
            ]
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "total energy schema"
}
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{
    "units": "eV", 
    "name": "total_energy", 
    "value": -123.43573079
}

Zero Point Energy

Some residual thermal vibrational energy is left at zero temperature due to quantum effects, and is referred to as Zero Point Energy.

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{
    "schemaId": "properties-directory-scalar-zero-point-energy", 
    "allOf": [
        {
            "required": [
                "name", 
                "units"
            ], 
            "schemaId": "core-reusable-energy", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ], 
            "properties": {
                "units": {
                    "anyOf": [
                        {
                            "enum": [
                                "kJ/mol", 
                                "eV", 
                                "J/mol", 
                                "hartree", 
                                "cm-1", 
                                "rydberg", 
                                "eV/atom"
                            ]
                        }, 
                        {
                            "enum": [
                                "eV/A^2"
                            ]
                        }
                    ]
                }, 
                "name": {
                    "type": "string"
                }
            }, 
            "title": "energy schema"
        }
    ], 
    "properties": {
        "name": {
            "enum": [
                "zero_point_energy"
            ]
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "zero point energy schema"
}
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{
    "units": "eV", 
    "name": "zero_point_energy", 
    "value": -123.43573079
}

Fermi Energy

The Fermi energy marks the highest occupied energy level in a solid.

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{
    "schemaId": "properties-directory-scalar-fermi-energy", 
    "allOf": [
        {
            "required": [
                "name", 
                "units"
            ], 
            "schemaId": "core-reusable-energy", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ], 
            "properties": {
                "units": {
                    "anyOf": [
                        {
                            "enum": [
                                "kJ/mol", 
                                "eV", 
                                "J/mol", 
                                "hartree", 
                                "cm-1", 
                                "rydberg", 
                                "eV/atom"
                            ]
                        }, 
                        {
                            "enum": [
                                "eV/A^2"
                            ]
                        }
                    ]
                }, 
                "name": {
                    "type": "string"
                }
            }, 
            "title": "energy schema"
        }
    ], 
    "properties": {
        "name": {
            "enum": [
                "fermi_energy"
            ]
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "fermi energy schema"
}
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{
    "units": "eV", 
    "name": "fermi_energy", 
    "value": -1.2
}

Total Energy Contributions

Total energy contributions contains information about the components in the total energy of the unit cell. The contributions available will depend on the type of method and software used.

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{
    "schemaId": "properties-directory-non-scalar-total-energy-contributions", 
    "type": "object", 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "properties": {
        "PAWDoubleCounting2": {
            "properties": {
                "name": {
                    "enum": [
                        "PAW_double-counting_correction_2"
                    ]
                }
            }, 
            "description": "double counting correction 2", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ]
        }, 
        "PAWDoubleCounting3": {
            "properties": {
                "name": {
                    "enum": [
                        "PAW_double-counting_correction_3"
                    ]
                }
            }, 
            "description": "double counting correction 3", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ]
        }, 
        "harrisFoulkes": {
            "properties": {
                "name": {
                    "enum": [
                        "harris_foulkes"
                    ]
                }
            }, 
            "description": "non self-consitent energy based on an input charge density", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ]
        }, 
        "ewald": {
            "properties": {
                "name": {
                    "enum": [
                        "ewald"
                    ]
                }
            }, 
            "description": "summation of interaction energies at long length scales due to coloumbic interactions", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ]
        }, 
        "hartreeFock": {
            "properties": {
                "name": {
                    "enum": [
                        "hartree_fock"
                    ]
                }
            }, 
            "description": "hartree-fock contribution", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ]
        }, 
        "exchange": {
            "properties": {
                "name": {
                    "enum": [
                        "exchange"
                    ]
                }
            }, 
            "description": "exchange energy", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ]
        }, 
        "alphaZ": {
            "properties": {
                "name": {
                    "enum": [
                        "alphaZ"
                    ]
                }
            }, 
            "description": "divergent electrostatic ion interaction in compensating electron gas", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ]
        }, 
        "oneElectron": {
            "properties": {
                "name": {
                    "enum": [
                        "one_electron"
                    ]
                }
            }, 
            "description": "kinetic + pseudopotential energy", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ]
        }, 
        "atomicEnergy": {
            "properties": {
                "name": {
                    "enum": [
                        "atomic_energy"
                    ]
                }
            }, 
            "description": "kinetic energy of wavefunctions in the atomic limit", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ]
        }, 
        "units": {
            "enum": [
                "kJ/mol", 
                "eV", 
                "J/mol", 
                "hartree", 
                "cm-1", 
                "rydberg", 
                "eV/atom"
            ]
        }, 
        "eigenvalues": {
            "properties": {
                "name": {
                    "enum": [
                        "eigenvalues"
                    ]
                }
            }, 
            "description": "sum of one electron energies of kinetic, electrostatic, and exchange correlation", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ]
        }, 
        "hartree": {
            "properties": {
                "name": {
                    "enum": [
                        "hartree"
                    ]
                }
            }, 
            "description": "energy due to coulomb potential", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ]
        }, 
        "temperatureEntropy": {
            "properties": {
                "name": {
                    "enum": [
                        "temperature_entropy"
                    ]
                }
            }, 
            "description": "product of temperature and configurational entropy", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ]
        }, 
        "exchangeCorrelation": {
            "properties": {
                "name": {
                    "enum": [
                        "exchange_correlation"
                    ]
                }
            }, 
            "description": "exchange and correlation energy per particle", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ]
        }, 
        "name": {
            "enum": [
                "total_energy_contributions"
            ]
        }
    }, 
    "title": "total energy contributions schema"
}
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{
    "PAWDoubleCounting2": {
        "name": "PAW_double-counting_correction_2", 
        "value": 12658.30538857
    }, 
    "PAWDoubleCounting3": {
        "name": "PAW_double-counting_correction_3", 
        "value": -12074.85364512
    }, 
    "ewald": {
        "name": "ewald", 
        "value": 128376.45871064
    }, 
    "name": "total_energy_contributions", 
    "exchange": {
        "name": "exchange", 
        "value": 0
    }, 
    "alphaZ": {
        "name": "alphaZ", 
        "value": 1056.91493097
    }, 
    "atomicEnergy": {
        "name": "atomic_energy", 
        "value": 15740.5725788
    }, 
    "units": "eV", 
    "eigenvalues": {
        "name": "eigenvalues", 
        "value": -577.80127102
    }, 
    "hartree": {
        "name": "hartree", 
        "value": -145344.66902862
    }, 
    "temperatureEntropy": {
        "name": "temperature_entropy", 
        "value": -0.00032545
    }, 
    "exchangeCorrelation": {
        "name": "exchange_correlation", 
        "value": 41.63693035
    }
}

Formation Energy

The Formation energy represents the energy required to create a defect in an otherwise perfect solid structure.

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{
    "schemaId": "properties-directory-scalar-formation-energy", 
    "allOf": [
        {
            "required": [
                "name", 
                "units"
            ], 
            "schemaId": "core-reusable-energy", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ], 
            "properties": {
                "units": {
                    "anyOf": [
                        {
                            "enum": [
                                "kJ/mol", 
                                "eV", 
                                "J/mol", 
                                "hartree", 
                                "cm-1", 
                                "rydberg", 
                                "eV/atom"
                            ]
                        }, 
                        {
                            "enum": [
                                "eV/A^2"
                            ]
                        }
                    ]
                }, 
                "name": {
                    "type": "string"
                }
            }, 
            "title": "energy schema"
        }
    ], 
    "properties": {
        "name": {
            "enum": [
                "formation_energy"
            ]
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "formation energy schema"
}
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{
    "units": "eV", 
    "name": "formation_energy", 
    "value": -123.43573079
}

Surface Energy

The energy of a surface can also be computed.

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{
    "schemaId": "properties-directory-scalar-surface-energy", 
    "allOf": [
        {
            "required": [
                "name", 
                "units"
            ], 
            "schemaId": "core-reusable-energy", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ], 
            "properties": {
                "units": {
                    "anyOf": [
                        {
                            "enum": [
                                "kJ/mol", 
                                "eV", 
                                "J/mol", 
                                "hartree", 
                                "cm-1", 
                                "rydberg", 
                                "eV/atom"
                            ]
                        }, 
                        {
                            "enum": [
                                "eV/A^2"
                            ]
                        }
                    ]
                }, 
                "name": {
                    "type": "string"
                }
            }, 
            "title": "energy schema"
        }
    ], 
    "properties": {
        "name": {
            "enum": [
                "surface_energy"
            ]
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "surface energy schema"
}
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{
    "units": "eV/A^2", 
    "name": "surface_energy", 
    "value": 0.02
}

Pressure

Pressure contains the average internal pressure of the unit cell.

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{
    "description": "average pressure in unit cell", 
    "allOf": [
        {
            "schemaId": "core-primitive-scalar", 
            "required": [
                "value"
            ], 
            "type": "object", 
            "properties": {
                "value": {
                    "type": "number"
                }
            }, 
            "title": "scalar schema"
        }
    ], 
    "schemaId": "properties-directory-scalar-pressure", 
    "title": "pressure", 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "properties": {
        "units": {
            "enum": [
                "kbar", 
                "pa"
            ]
        }, 
        "name": {
            "enum": [
                "pressure"
            ]
        }
    }
}
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{
    "units": "kbar", 
    "name": "pressure", 
    "value": -27.345
}

Total Force

This is the total average force present within the crystal structure.

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{
    "schemaId": "properties-directory-scalar-total-force", 
    "allOf": [
        {
            "schemaId": "core-primitive-scalar", 
            "required": [
                "value"
            ], 
            "type": "object", 
            "properties": {
                "value": {
                    "type": "number"
                }
            }, 
            "title": "scalar schema"
        }
    ], 
    "properties": {
        "units": {
            "enum": [
                "eV/bohr", 
                "eV/angstrom", 
                "rydberg/a.u.", 
                "newton", 
                "kg*m/s^2", 
                "eV/a.u."
            ]
        }, 
        "name": {
            "enum": [
                "total_force"
            ]
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "total forces schema"
}
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{
    "units": "eV/angstrom", 
    "name": "total_force", 
    "value": 1e-06
}

Non-Scalar Properties

Bandstructure

Band structure shows the energy of electronic states (bands) as a function of k-point position throughout the cell.

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{
    "schemaId": "properties-directory-non-scalar-band-structure", 
    "allOf": [
        {
            "required": [
                "xAxis", 
                "yAxis"
            ], 
            "schemaId": "core-abstract-2d-plot", 
            "allOf": [
                {
                    "schemaId": "core-abstract-2d-data", 
                    "required": [
                        "xDataArray", 
                        "yDataSeries"
                    ], 
                    "type": "object", 
                    "properties": {
                        "xDataArray": {
                            "type": "array", 
                            "description": "array containing values of x Axis"
                        }, 
                        "yDataSeries": {
                            "items": {
                                "minItems": 1, 
                                "items": {
                                    "type": [
                                        "number", 
                                        "string"
                                    ]
                                }, 
                                "type": "array"
                            }, 
                            "schemaId": "core-primitive-1d-data-series", 
                            "type": "array", 
                            "title": "1 dimension data series schema"
                        }
                    }, 
                    "title": "2 dimension data schema"
                }
            ], 
            "properties": {
                "legend": {
                    "minItems": 1, 
                    "type": "array", 
                    "description": "Legend of y Axis data series"
                }, 
                "xAxis": {
                    "schemaId": "core-primitive-axis", 
                    "required": [
                        "label"
                    ], 
                    "properties": {
                        "units": {
                            "type": "string", 
                            "description": "units for an axis"
                        }, 
                        "label": {
                            "type": "string", 
                            "description": "label of an axis object"
                        }
                    }, 
                    "description": "x Axis object", 
                    "title": "axis schema"
                }, 
                "yAxis": {
                    "schemaId": "core-primitive-axis", 
                    "required": [
                        "label"
                    ], 
                    "properties": {
                        "units": {
                            "type": "string", 
                            "description": "units for an axis"
                        }, 
                        "label": {
                            "type": "string", 
                            "description": "label of an axis object"
                        }
                    }, 
                    "description": "y Axis object", 
                    "title": "axis schema"
                }
            }, 
            "title": "2 dimension plot schema"
        }
    ], 
    "properties": {
        "spin": {
            "items": {
                "enum": [
                    0.5, 
                    -0.5
                ], 
                "type": "number"
            }, 
            "type": "array", 
            "description": "spin of each band"
        }, 
        "name": {
            "enum": [
                "band_structure"
            ]
        }, 
        "xAxis": {
            "properties": {
                "units": {
                    "enum": [
                        "km", 
                        "m", 
                        "pm", 
                        "nm", 
                        "angstrom", 
                        "a.u.", 
                        "bohr", 
                        "fractional", 
                        "crystal", 
                        "cartesian", 
                        "alat"
                    ]
                }, 
                "label": {
                    "enum": [
                        "kpoints"
                    ]
                }
            }
        }, 
        "yAxis": {
            "properties": {
                "units": {
                    "enum": [
                        "kJ/mol", 
                        "eV", 
                        "J/mol", 
                        "hartree", 
                        "cm-1", 
                        "rydberg", 
                        "eV/atom"
                    ]
                }, 
                "label": {
                    "enum": [
                        "energy"
                    ]
                }
            }
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "band structure schema"
}
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{
    "yDataSeries": [
        [
            12.1, 
            12.5
        ], 
        [
            11.1, 
            11.5
        ], 
        [
            10.1, 
            10.5
        ], 
        [
            9.5, 
            8.5
        ]
    ], 
    "yAxis": {
        "units": "eV", 
        "label": "energy"
    }, 
    "xDataArray": [
        [
            0, 
            0, 
            0
        ], 
        [
            0.5, 
            0.5, 
            0.5
        ]
    ], 
    "xAxis": {
        "units": "crystal", 
        "label": "kpoints"
    }, 
    "spin": [
        0.5, 
        0.5, 
        0.5, 
        0.5
    ], 
    "name": "band_structure"
}

Band Gaps

Band gap is the difference in energy from the highest occupied electronic state (Fermi energy at 0K) to the lowest unoccupied state.

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{
    "description": "contains band gap values", 
    "title": "band gaps schema", 
    "schemaId": "properties-directory-non-scalar-band-gaps", 
    "required": [
        "name"
    ], 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "properties": {
        "eigenvalues": {
            "items": {
                "properties": {
                    "kpoint": {
                        "title": "array of 3 number elements schema", 
                        "minItems": 3, 
                        "items": {
                            "type": "number"
                        }, 
                        "schemaId": "core-primitive-array-of-3-numbers", 
                        "maxItems": 3, 
                        "type": "array"
                    }, 
                    "weight": {
                        "type": "number"
                    }, 
                    "eigenvalues": {
                        "items": {
                            "properties": {
                                "energies": {
                                    "type": "array"
                                }, 
                                "spin": {
                                    "type": "number"
                                }, 
                                "occupations": {
                                    "type": "array"
                                }
                            }
                        }, 
                        "type": "array"
                    }
                }
            }, 
            "type": "array"
        }, 
        "values": {
            "items": {
                "required": [
                    "type"
                ], 
                "schemaId": "core-reusable-band-gap", 
                "allOf": [
                    {
                        "schemaId": "core-primitive-scalar", 
                        "required": [
                            "value"
                        ], 
                        "type": "object", 
                        "properties": {
                            "value": {
                                "type": "number"
                            }
                        }, 
                        "title": "scalar schema"
                    }
                ], 
                "properties": {
                    "units": {
                        "enum": [
                            "kJ/mol", 
                            "eV", 
                            "J/mol", 
                            "hartree", 
                            "cm-1", 
                            "rydberg", 
                            "eV/atom"
                        ]
                    }, 
                    "kpointConduction": {
                        "description": "kpoint inside conduction band in crystal coordinates", 
                        "title": "array of 3 number elements schema", 
                        "minItems": 3, 
                        "items": {
                            "type": "number"
                        }, 
                        "schemaId": "core-primitive-array-of-3-numbers", 
                        "maxItems": 3, 
                        "type": "array"
                    }, 
                    "kpointValence": {
                        "description": "kpoint inside valence band in crystal coordinates", 
                        "title": "array of 3 number elements schema", 
                        "minItems": 3, 
                        "items": {
                            "type": "number"
                        }, 
                        "schemaId": "core-primitive-array-of-3-numbers", 
                        "maxItems": 3, 
                        "type": "array"
                    }, 
                    "type": {
                        "enum": [
                            "direct", 
                            "indirect"
                        ], 
                        "type": "string"
                    }
                }, 
                "title": "band gap schema"
            }, 
            "type": "array"
        }, 
        "name": {
            "enum": [
                "band_gaps"
            ]
        }
    }
}
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{
    "values": [
        {
            "units": "rydberg", 
            "kpointConduction": [
                0, 
                0, 
                0
            ], 
            "kpointValence": [
                0, 
                0, 
                0
            ], 
            "value": 0.0947, 
            "type": "direct"
        }, 
        {
            "units": "rydberg", 
            "type": "indirect", 
            "value": 0.0
        }
    ], 
    "name": "band_gaps"
}

Electronic Density of States

Density of states contains information on the number of electronic states as a function of energy. It may include the atom resolved partial density of states and electron states in some cases. In addition it may also contain information about each atom’s spin state as well.

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{
    "allOf": [
        {
            "required": [
                "xAxis", 
                "yAxis"
            ], 
            "schemaId": "core-abstract-2d-plot", 
            "allOf": [
                {
                    "schemaId": "core-abstract-2d-data", 
                    "required": [
                        "xDataArray", 
                        "yDataSeries"
                    ], 
                    "type": "object", 
                    "properties": {
                        "xDataArray": {
                            "type": "array", 
                            "description": "array containing values of x Axis"
                        }, 
                        "yDataSeries": {
                            "items": {
                                "minItems": 1, 
                                "items": {
                                    "type": [
                                        "number", 
                                        "string"
                                    ]
                                }, 
                                "type": "array"
                            }, 
                            "schemaId": "core-primitive-1d-data-series", 
                            "type": "array", 
                            "title": "1 dimension data series schema"
                        }
                    }, 
                    "title": "2 dimension data schema"
                }
            ], 
            "properties": {
                "legend": {
                    "minItems": 1, 
                    "type": "array", 
                    "description": "Legend of y Axis data series"
                }, 
                "xAxis": {
                    "schemaId": "core-primitive-axis", 
                    "required": [
                        "label"
                    ], 
                    "properties": {
                        "units": {
                            "type": "string", 
                            "description": "units for an axis"
                        }, 
                        "label": {
                            "type": "string", 
                            "description": "label of an axis object"
                        }
                    }, 
                    "description": "x Axis object", 
                    "title": "axis schema"
                }, 
                "yAxis": {
                    "schemaId": "core-primitive-axis", 
                    "required": [
                        "label"
                    ], 
                    "properties": {
                        "units": {
                            "type": "string", 
                            "description": "units for an axis"
                        }, 
                        "label": {
                            "type": "string", 
                            "description": "label of an axis object"
                        }
                    }, 
                    "description": "y Axis object", 
                    "title": "axis schema"
                }
            }, 
            "title": "2 dimension plot schema"
        }
    ], 
    "schemaId": "properties-directory-non-scalar-density-of-states", 
    "title": "density of states schema", 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "type": "object", 
    "properties": {
        "legend": {
            "items": {
                "type": "object", 
                "properties": {
                    "index": {
                        "type": "integer", 
                        "description": "index inside sub-array of atoms of the same element type"
                    }, 
                    "electronicState": {
                        "pattern": "^([1-5]{1})?(s|p|d|f|g).*$", 
                        "type": "string", 
                        "description": "electronic character and shell of PDOS, such as `1s` or `s`, or `total`"
                    }, 
                    "spin": {
                        "enum": [
                            0.5, 
                            -0.5
                        ], 
                        "type": "number", 
                        "description": "spin of the electronic state"
                    }, 
                    "element": {
                        "type": "string", 
                        "description": "chemical element"
                    }
                }
            }
        }, 
        "name": {
            "enum": [
                "density_of_states"
            ]
        }, 
        "xAxis": {
            "properties": {
                "units": {
                    "enum": [
                        "kJ/mol", 
                        "eV", 
                        "J/mol", 
                        "hartree", 
                        "cm-1", 
                        "rydberg", 
                        "eV/atom"
                    ]
                }, 
                "label": {
                    "enum": [
                        "energy"
                    ]
                }
            }
        }, 
        "yAxis": {
            "properties": {
                "units": {
                    "enum": [
                        "states/unitcell"
                    ]
                }, 
                "label": {
                    "enum": [
                        "density of states"
                    ]
                }
            }
        }
    }
}
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{
    "yDataSeries": [
        [
            12.1, 
            12.5
        ], 
        [
            11.1, 
            11.5
        ], 
        [
            10.1, 
            10.5
        ], 
        [
            9.5, 
            8.5
        ]
    ], 
    "yAxis": {
        "units": "states/unitcell", 
        "label": "density of states"
    }, 
    "name": "density_of_states", 
    "xAxis": {
        "units": "eV", 
        "label": "energy"
    }, 
    "legend": [
        {
            "index": 1, 
            "electronicState": "2s", 
            "spin": 0.5, 
            "element": "C"
        }, 
        {
            "index": 2, 
            "electronicState": "2p", 
            "spin": 0.5, 
            "element": "C"
        }
    ], 
    "xDataArray": [
        [
            0, 
            0, 
            0
        ], 
        [
            0.5, 
            0.5, 
            0.5
        ]
    ]
}

Reaction Energy Profile

The energy profile of a chemical reaction is a representation of its energetic pathway, followed by the reactants as they are transformed into products.

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{
    "schemaId": "properties-directory-non-scalar-reaction-energy-profile", 
    "allOf": [
        {
            "required": [
                "xAxis", 
                "yAxis"
            ], 
            "schemaId": "core-abstract-2d-plot", 
            "allOf": [
                {
                    "schemaId": "core-abstract-2d-data", 
                    "required": [
                        "xDataArray", 
                        "yDataSeries"
                    ], 
                    "type": "object", 
                    "properties": {
                        "xDataArray": {
                            "type": "array", 
                            "description": "array containing values of x Axis"
                        }, 
                        "yDataSeries": {
                            "items": {
                                "minItems": 1, 
                                "items": {
                                    "type": [
                                        "number", 
                                        "string"
                                    ]
                                }, 
                                "type": "array"
                            }, 
                            "schemaId": "core-primitive-1d-data-series", 
                            "type": "array", 
                            "title": "1 dimension data series schema"
                        }
                    }, 
                    "title": "2 dimension data schema"
                }
            ], 
            "properties": {
                "legend": {
                    "minItems": 1, 
                    "type": "array", 
                    "description": "Legend of y Axis data series"
                }, 
                "xAxis": {
                    "schemaId": "core-primitive-axis", 
                    "required": [
                        "label"
                    ], 
                    "properties": {
                        "units": {
                            "type": "string", 
                            "description": "units for an axis"
                        }, 
                        "label": {
                            "type": "string", 
                            "description": "label of an axis object"
                        }
                    }, 
                    "description": "x Axis object", 
                    "title": "axis schema"
                }, 
                "yAxis": {
                    "schemaId": "core-primitive-axis", 
                    "required": [
                        "label"
                    ], 
                    "properties": {
                        "units": {
                            "type": "string", 
                            "description": "units for an axis"
                        }, 
                        "label": {
                            "type": "string", 
                            "description": "label of an axis object"
                        }
                    }, 
                    "description": "y Axis object", 
                    "title": "axis schema"
                }
            }, 
            "title": "2 dimension plot schema"
        }
    ], 
    "properties": {
        "name": {
            "enum": [
                "reaction_energy_profile"
            ]
        }, 
        "xAxis": {
            "properties": {
                "label": {
                    "enum": [
                        "reaction coordinate"
                    ]
                }
            }
        }, 
        "yAxis": {
            "properties": {
                "units": {
                    "enum": [
                        "kJ/mol", 
                        "eV", 
                        "J/mol", 
                        "hartree", 
                        "cm-1", 
                        "rydberg", 
                        "eV/atom"
                    ]
                }, 
                "label": {
                    "enum": [
                        "energy"
                    ]
                }
            }
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "reaction energy profile schema"
}
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{
    "yDataSeries": [
        [
            0.0, 
            0.0336637211, 
            0.1282952413, 
            0.2032895454, 
            0.1282953846, 
            0.0336637671, 
            -5.3e-09
        ]
    ], 
    "yAxis": {
        "units": "eV", 
        "label": "energy"
    }, 
    "name": "reaction_energy_profile", 
    "xAxis": {
        "label": "reaction coordinate"
    }, 
    "xDataArray": [
        0.0, 
        0.1932731666, 
        0.3596118308, 
        0.4999998753, 
        0.640387977, 
        0.8067267116, 
        1.0
    ]
}

Reaction Energy Barrier

The Reaction Energy Barrier marks the highest energy state encountered during the course of the progress of a chemical reaction.

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{
    "schemaId": "properties-directory-scalar-reaction-energy-barrier", 
    "allOf": [
        {
            "required": [
                "name", 
                "units"
            ], 
            "schemaId": "core-reusable-energy", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ], 
            "properties": {
                "units": {
                    "anyOf": [
                        {
                            "enum": [
                                "kJ/mol", 
                                "eV", 
                                "J/mol", 
                                "hartree", 
                                "cm-1", 
                                "rydberg", 
                                "eV/atom"
                            ]
                        }, 
                        {
                            "enum": [
                                "eV/A^2"
                            ]
                        }
                    ]
                }, 
                "name": {
                    "type": "string"
                }
            }, 
            "title": "energy schema"
        }
    ], 
    "properties": {
        "name": {
            "enum": [
                "reaction_energy_barrier"
            ]
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "reaction energy barrier schema"
}
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{
    "units": "eV", 
    "name": "reaction_energy_barrier", 
    "value": -123.43573079
}

Phonon Dispersions

Lattice vibrations can be plotted in the form of phonon frequency dispersion plots across the reciprocal k-space of the crystal structure.

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{
    "schemaId": "properties-directory-non-scalar-phonon-dispersions", 
    "allOf": [
        {
            "required": [
                "xAxis", 
                "yAxis"
            ], 
            "schemaId": "core-abstract-2d-plot", 
            "allOf": [
                {
                    "schemaId": "core-abstract-2d-data", 
                    "required": [
                        "xDataArray", 
                        "yDataSeries"
                    ], 
                    "type": "object", 
                    "properties": {
                        "xDataArray": {
                            "type": "array", 
                            "description": "array containing values of x Axis"
                        }, 
                        "yDataSeries": {
                            "items": {
                                "minItems": 1, 
                                "items": {
                                    "type": [
                                        "number", 
                                        "string"
                                    ]
                                }, 
                                "type": "array"
                            }, 
                            "schemaId": "core-primitive-1d-data-series", 
                            "type": "array", 
                            "title": "1 dimension data series schema"
                        }
                    }, 
                    "title": "2 dimension data schema"
                }
            ], 
            "properties": {
                "legend": {
                    "minItems": 1, 
                    "type": "array", 
                    "description": "Legend of y Axis data series"
                }, 
                "xAxis": {
                    "schemaId": "core-primitive-axis", 
                    "required": [
                        "label"
                    ], 
                    "properties": {
                        "units": {
                            "type": "string", 
                            "description": "units for an axis"
                        }, 
                        "label": {
                            "type": "string", 
                            "description": "label of an axis object"
                        }
                    }, 
                    "description": "x Axis object", 
                    "title": "axis schema"
                }, 
                "yAxis": {
                    "schemaId": "core-primitive-axis", 
                    "required": [
                        "label"
                    ], 
                    "properties": {
                        "units": {
                            "type": "string", 
                            "description": "units for an axis"
                        }, 
                        "label": {
                            "type": "string", 
                            "description": "label of an axis object"
                        }
                    }, 
                    "description": "y Axis object", 
                    "title": "axis schema"
                }
            }, 
            "title": "2 dimension plot schema"
        }
    ], 
    "properties": {
        "name": {
            "enum": [
                "phonon_dispersions"
            ]
        }, 
        "xAxis": {
            "properties": {
                "units": {
                    "enum": [
                        "km", 
                        "m", 
                        "pm", 
                        "nm", 
                        "angstrom", 
                        "a.u.", 
                        "bohr", 
                        "fractional", 
                        "crystal", 
                        "cartesian", 
                        "alat"
                    ]
                }, 
                "label": {
                    "enum": [
                        "qpoints"
                    ]
                }
            }
        }, 
        "yAxis": {
            "properties": {
                "units": {
                    "enum": [
                        "cm-1", 
                        "THz", 
                        "meV"
                    ]
                }, 
                "label": {
                    "enum": [
                        "frequency"
                    ]
                }
            }
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "phonon band structure schema"
}
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{
    "yDataSeries": [
        [
            -6e-06, 
            -6e-06, 
            -5e-06, 
            734.596987, 
            734.618837, 
            734.618837
        ], 
        [
            -6.859784, 
            -6.859784, 
            36.443014, 
            730.782803, 
            731.143013, 
            731.143013
        ]
    ], 
    "yAxis": {
        "units": "cm-1", 
        "label": "frequency"
    }, 
    "name": "phonon_dispersions", 
    "xAxis": {
        "units": "crystal", 
        "label": "qpoints"
    }, 
    "xDataArray": [
        [
            0, 
            0, 
            0
        ], 
        [
            0.5, 
            0.05, 
            0.05
        ]
    ]
}

Phonon Density of States

The Density of States for phonons can also be computed.

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{
    "allOf": [
        {
            "required": [
                "xAxis", 
                "yAxis"
            ], 
            "schemaId": "core-abstract-2d-plot", 
            "allOf": [
                {
                    "schemaId": "core-abstract-2d-data", 
                    "required": [
                        "xDataArray", 
                        "yDataSeries"
                    ], 
                    "type": "object", 
                    "properties": {
                        "xDataArray": {
                            "type": "array", 
                            "description": "array containing values of x Axis"
                        }, 
                        "yDataSeries": {
                            "items": {
                                "minItems": 1, 
                                "items": {
                                    "type": [
                                        "number", 
                                        "string"
                                    ]
                                }, 
                                "type": "array"
                            }, 
                            "schemaId": "core-primitive-1d-data-series", 
                            "type": "array", 
                            "title": "1 dimension data series schema"
                        }
                    }, 
                    "title": "2 dimension data schema"
                }
            ], 
            "properties": {
                "legend": {
                    "minItems": 1, 
                    "type": "array", 
                    "description": "Legend of y Axis data series"
                }, 
                "xAxis": {
                    "schemaId": "core-primitive-axis", 
                    "required": [
                        "label"
                    ], 
                    "properties": {
                        "units": {
                            "type": "string", 
                            "description": "units for an axis"
                        }, 
                        "label": {
                            "type": "string", 
                            "description": "label of an axis object"
                        }
                    }, 
                    "description": "x Axis object", 
                    "title": "axis schema"
                }, 
                "yAxis": {
                    "schemaId": "core-primitive-axis", 
                    "required": [
                        "label"
                    ], 
                    "properties": {
                        "units": {
                            "type": "string", 
                            "description": "units for an axis"
                        }, 
                        "label": {
                            "type": "string", 
                            "description": "label of an axis object"
                        }
                    }, 
                    "description": "y Axis object", 
                    "title": "axis schema"
                }
            }, 
            "title": "2 dimension plot schema"
        }
    ], 
    "schemaId": "properties-directory-non-scalar-phonon-dos", 
    "title": "Phonon density of states schema", 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "type": "object", 
    "properties": {
        "name": {
            "enum": [
                "phonon_dos"
            ]
        }, 
        "xAxis": {
            "properties": {
                "units": {
                    "enum": [
                        "cm-1", 
                        "THz", 
                        "meV"
                    ]
                }, 
                "label": {
                    "enum": [
                        "frequency"
                    ]
                }
            }
        }, 
        "yAxis": {
            "properties": {
                "units": {
                    "enum": [
                        "states/cm-1", 
                        "states/THz", 
                        "states/meV"
                    ]
                }, 
                "label": {
                    "enum": [
                        "Phonon DOS"
                    ]
                }
            }
        }
    }
}
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{
    "yDataSeries": [
        [
            0.0001433, 
            0.00011382, 
            8.7721e-05, 
            6.502e-05, 
            4.5713e-05, 
            2.9799e-05, 
            1.7279e-05, 
            8.1527e-06, 
            2.4197e-06
        ]
    ], 
    "yAxis": {
        "units": "states/cm-1", 
        "label": "Phonon DOS"
    }, 
    "name": "phonon_dos", 
    "xAxis": {
        "units": "cm-1", 
        "label": "frequency"
    }, 
    "xDataArray": [
        [
            565.0, 
            566.0, 
            567.0, 
            568.0, 
            569.0, 
            570.0, 
            571.0, 
            572.0, 
            573.0
        ]
    ]
}

Stress Tensor

Stress tensor contains a 3x3 matrix of the stress components of the unit cell.

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{
    "schemaId": "properties-directory-non-scalar-stress-tensor", 
    "properties": {
        "units": {
            "enum": [
                "kbar", 
                "pa"
            ]
        }, 
        "name": {
            "enum": [
                "stress_tensor"
            ]
        }, 
        "value": {
            "title": "3 dimensional tensor schema", 
            "minItems": 3, 
            "items": {
                "title": "array of 3 number elements schema", 
                "minItems": 3, 
                "items": {
                    "type": "number"
                }, 
                "schemaId": "core-primitive-array-of-3-numbers", 
                "maxItems": 3, 
                "type": "array"
            }, 
            "schemaId": "core-abstract-3d-tensor", 
            "maxItems": 3, 
            "type": "array"
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "stress tensor schema"
}
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{
    "units": "kbar", 
    "name": "stress_tensor", 
    "value": [
        [
            3, 
            0, 
            0
        ], 
        [
            0, 
            3, 
            0
        ], 
        [
            0, 
            0, 
            3
        ]
    ]
}

Elemental Properties

Atomic Radius

The atomic radius represents the average distance between the nucleus of an atom and the edges of its surrounding electron cloud.

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{
    "description": "atomic radius", 
    "allOf": [
        {
            "schemaId": "core-primitive-scalar", 
            "required": [
                "value"
            ], 
            "type": "object", 
            "properties": {
                "value": {
                    "type": "number"
                }
            }, 
            "title": "scalar schema"
        }
    ], 
    "schemaId": "properties-directory-elemental-atomic-radius", 
    "title": "atomic radius", 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "properties": {
        "units": {
            "enum": [
                "km", 
                "m", 
                "pm", 
                "nm", 
                "angstrom", 
                "a.u.", 
                "bohr", 
                "fractional", 
                "crystal", 
                "cartesian", 
                "alat"
            ]
        }, 
        "name": {
            "enum": [
                "atomic_radius"
            ]
        }
    }
}
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{
    "name": "atomic_radius", 
    "value": 4
}

Electronegativity

The electronegativity describes the capacity of an atom to attract the electrons involved in chemical bonding.

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{
    "description": "electronegativity for the element (Pauling scale)", 
    "allOf": [
        {
            "schemaId": "core-primitive-scalar", 
            "required": [
                "value"
            ], 
            "type": "object", 
            "properties": {
                "value": {
                    "type": "number"
                }
            }, 
            "title": "scalar schema"
        }
    ], 
    "schemaId": "properties-directory-elemental-electronegativity", 
    "title": "electronegativity", 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "properties": {
        "name": {
            "enum": [
                "electronegativity"
            ]
        }
    }
}
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{
    "name": "electronegativity", 
    "value": 1.1
}

Ionization Potential

The ionization energy (or potential) measures the energy required to strip an atom from its most loosely bound valence electron.

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{
    "description": "ionization potential for the element", 
    "allOf": [
        {
            "schemaId": "core-primitive-scalar", 
            "required": [
                "value"
            ], 
            "type": "object", 
            "properties": {
                "value": {
                    "type": "number"
                }
            }, 
            "title": "scalar schema"
        }
    ], 
    "schemaId": "properties-directory-elemental-ionization-potential", 
    "title": "ionization potential", 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "properties": {
        "units": {
            "enum": [
                "kJ/mol", 
                "eV", 
                "J/mol", 
                "hartree", 
                "cm-1", 
                "rydberg", 
                "eV/atom"
            ]
        }, 
        "name": {
            "enum": [
                "ionization_potential"
            ]
        }
    }
}
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{
    "name": "ionization_potential", 
    "value": 7.7
}

Structural Properties

Atomic Forces

Forces may exist between atoms in a crystal structure if they are displaced away from their equilibrium configuration.

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{
    "schemaId": "properties-directory-structural-atomic-forces", 
    "description": "coordinates of atoms by ids, vector, unitless", 
    "properties": {
        "units": {
            "enum": [
                "eV/bohr", 
                "eV/angstrom", 
                "rydberg/a.u.", 
                "newton", 
                "kg*m/s^2", 
                "eV/a.u."
            ]
        }, 
        "values": {
            "items": {
                "properties": {
                    "value": {
                        "schemaId": "core-abstract-vector", 
                        "anyOf": [
                            {
                                "title": "array of 3 number elements schema", 
                                "minItems": 3, 
                                "items": {
                                    "type": "number"
                                }, 
                                "schemaId": "core-primitive-array-of-3-numbers", 
                                "maxItems": 3, 
                                "type": "array"
                            }, 
                            {
                                "title": "array of 3 boolean elements schema", 
                                "minItems": 3, 
                                "items": {
                                    "type": "boolean"
                                }, 
                                "schemaId": "core-primitive-array-of-3-booleans", 
                                "maxItems": 3, 
                                "type": "array"
                            }
                        ], 
                        "title": "vector schema"
                    }
                }
            }, 
            "schemaId": "core-reusable-atomic-vectors", 
            "allOf": [
                {
                    "items": {
                        "uniqueItems": true, 
                        "type": "object", 
                        "properties": {
                            "id": {
                                "type": "integer", 
                                "description": "integer id of this entry"
                            }
                        }
                    }, 
                    "schemaId": "core-primitive-array-of-ids", 
                    "type": "array", 
                    "description": "array of objects containing integer id each", 
                    "title": "atomic ids"
                }
            ], 
            "title": "atomic vectors schema"
        }, 
        "name": {
            "enum": [
                "atomic_forces"
            ]
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "atomic forces"
}
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{
    "units": "eV/bohr", 
    "values": [
        {
            "id": 1, 
            "value": [
                -3.9e-07, 
                -2.4e-07, 
                0.0
            ]
        }, 
        {
            "id": 2, 
            "value": [
                3.9e-07, 
                2.4e-07, 
                0.0
            ]
        }
    ], 
    "name": "atomic_forces"
}

Atomic Coordinates

Contains information about the coordinates of atoms within the unit cell by id.

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{
    "schemaId": "properties-directory-structural-basis-atomic-coordinates", 
    "description": "coordinates of atoms by ids, vector, unitless", 
    "properties": {
        "units": {
            "enum": [
                "km", 
                "m", 
                "pm", 
                "nm", 
                "angstrom", 
                "a.u.", 
                "bohr", 
                "fractional", 
                "crystal", 
                "cartesian", 
                "alat"
            ]
        }, 
        "values": {
            "items": {
                "properties": {
                    "value": {
                        "schemaId": "core-abstract-vector", 
                        "anyOf": [
                            {
                                "title": "array of 3 number elements schema", 
                                "minItems": 3, 
                                "items": {
                                    "type": "number"
                                }, 
                                "schemaId": "core-primitive-array-of-3-numbers", 
                                "maxItems": 3, 
                                "type": "array"
                            }, 
                            {
                                "title": "array of 3 boolean elements schema", 
                                "minItems": 3, 
                                "items": {
                                    "type": "boolean"
                                }, 
                                "schemaId": "core-primitive-array-of-3-booleans", 
                                "maxItems": 3, 
                                "type": "array"
                            }
                        ], 
                        "title": "vector schema"
                    }
                }
            }, 
            "schemaId": "core-reusable-atomic-vectors", 
            "allOf": [
                {
                    "items": {
                        "uniqueItems": true, 
                        "type": "object", 
                        "properties": {
                            "id": {
                                "type": "integer", 
                                "description": "integer id of this entry"
                            }
                        }
                    }, 
                    "schemaId": "core-primitive-array-of-ids", 
                    "type": "array", 
                    "description": "array of objects containing integer id each", 
                    "title": "atomic ids"
                }
            ], 
            "title": "atomic vectors schema"
        }, 
        "name": {
            "enum": [
                "atomic_coordinates"
            ]
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "atomic coordinates"
}
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{
    "values": [
        {
            "id": 1, 
            "value": [
                0, 
                0, 
                0
            ]
        }, 
        {
            "id": 2, 
            "value": [
                0.25, 
                0.25, 
                0.25
            ]
        }
    ], 
    "name": "atomic_coordinates"
}

Atomic Elements

Contains an array of the elements in the unit cell and the atom id’s association with each atom.

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{
    "schemaId": "properties-directory-structural-basis-atomic-elements", 
    "description": "elements of atoms by ids, string, unitless", 
    "properties": {
        "values": {
            "items": {
                "properties": {
                    "value": {
                        "type": "string"
                    }
                }
            }, 
            "schemaId": "core-reusable-atomic-strings", 
            "allOf": [
                {
                    "items": {
                        "uniqueItems": true, 
                        "type": "object", 
                        "properties": {
                            "id": {
                                "type": "integer", 
                                "description": "integer id of this entry"
                            }
                        }
                    }, 
                    "schemaId": "core-primitive-array-of-ids", 
                    "type": "array", 
                    "description": "array of objects containing integer id each", 
                    "title": "atomic ids"
                }
            ], 
            "title": "atomic vectors schema"
        }, 
        "name": {
            "enum": [
                "atomic_elements"
            ]
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "atomic elements"
}
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[
    {
        "id": 1, 
        "value": "Si"
    }, 
    {
        "id": 2, 
        "value": "Si"
    }
]

Atomic Constraints

Contains information about the spatial constraints on the movement of atoms.

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{
    "schemaId": "properties-directory-structural-basis-atomic-constraints", 
    "description": "atomic constraints schema", 
    "properties": {
        "values": {
            "items": {
                "properties": {
                    "value": {
                        "schemaId": "core-abstract-vector", 
                        "anyOf": [
                            {
                                "title": "array of 3 number elements schema", 
                                "minItems": 3, 
                                "items": {
                                    "type": "number"
                                }, 
                                "schemaId": "core-primitive-array-of-3-numbers", 
                                "maxItems": 3, 
                                "type": "array"
                            }, 
                            {
                                "title": "array of 3 boolean elements schema", 
                                "minItems": 3, 
                                "items": {
                                    "type": "boolean"
                                }, 
                                "schemaId": "core-primitive-array-of-3-booleans", 
                                "maxItems": 3, 
                                "type": "array"
                            }
                        ], 
                        "title": "vector schema"
                    }
                }
            }, 
            "schemaId": "core-reusable-atomic-vectors", 
            "allOf": [
                {
                    "items": {
                        "uniqueItems": true, 
                        "type": "object", 
                        "properties": {
                            "id": {
                                "type": "integer", 
                                "description": "integer id of this entry"
                            }
                        }
                    }, 
                    "schemaId": "core-primitive-array-of-ids", 
                    "type": "array", 
                    "description": "array of objects containing integer id each", 
                    "title": "atomic ids"
                }
            ], 
            "title": "atomic vectors schema"
        }, 
        "name": {
            "enum": [
                "atomic_constraints"
            ]
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "atomic constraints"
}
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{
    "values": [
        {
            "id": 1, 
            "value": [
                true, 
                false, 
                true
            ]
        }, 
        {
            "id": 2, 
            "value": [
                false, 
                false, 
                true
            ]
        }
    ], 
    "name": "atomic_constraints"
}

Basis

Basis defines elemental and geometrical constitution of the unit cell.

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{
    "title": "basis schema", 
    "schemaId": "properties-directory-structural-basis", 
    "required": [
        "elements", 
        "coordinates"
    ], 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "type": "object", 
    "properties": {
        "elements": {
            "schemaId": "properties-directory-structural-basis-atomic-elements", 
            "properties": {
                "values": {
                    "items": {
                        "properties": {
                            "value": {
                                "type": "string"
                            }
                        }
                    }, 
                    "schemaId": "core-reusable-atomic-strings", 
                    "allOf": [
                        {
                            "items": {
                                "uniqueItems": true, 
                                "type": "object", 
                                "properties": {
                                    "id": {
                                        "type": "integer", 
                                        "description": "integer id of this entry"
                                    }
                                }
                            }, 
                            "schemaId": "core-primitive-array-of-ids", 
                            "type": "array", 
                            "description": "array of objects containing integer id each", 
                            "title": "atomic ids"
                        }
                    ], 
                    "title": "atomic vectors schema"
                }, 
                "name": {
                    "enum": [
                        "atomic_elements"
                    ]
                }
            }, 
            "description": "elements of atoms by ids, string, unitless", 
            "title": "atomic elements"
        }, 
        "coordinates": {
            "schemaId": "properties-directory-structural-basis-atomic-coordinates", 
            "properties": {
                "units": {
                    "enum": [
                        "km", 
                        "m", 
                        "pm", 
                        "nm", 
                        "angstrom", 
                        "a.u.", 
                        "bohr", 
                        "fractional", 
                        "crystal", 
                        "cartesian", 
                        "alat"
                    ]
                }, 
                "values": {
                    "items": {
                        "properties": {
                            "value": {
                                "schemaId": "core-abstract-vector", 
                                "anyOf": [
                                    {
                                        "title": "array of 3 number elements schema", 
                                        "minItems": 3, 
                                        "items": {
                                            "type": "number"
                                        }, 
                                        "schemaId": "core-primitive-array-of-3-numbers", 
                                        "maxItems": 3, 
                                        "type": "array"
                                    }, 
                                    {
                                        "title": "array of 3 boolean elements schema", 
                                        "minItems": 3, 
                                        "items": {
                                            "type": "boolean"
                                        }, 
                                        "schemaId": "core-primitive-array-of-3-booleans", 
                                        "maxItems": 3, 
                                        "type": "array"
                                    }
                                ], 
                                "title": "vector schema"
                            }
                        }
                    }, 
                    "schemaId": "core-reusable-atomic-vectors", 
                    "allOf": [
                        {
                            "items": {
                                "uniqueItems": true, 
                                "type": "object", 
                                "properties": {
                                    "id": {
                                        "type": "integer", 
                                        "description": "integer id of this entry"
                                    }
                                }
                            }, 
                            "schemaId": "core-primitive-array-of-ids", 
                            "type": "array", 
                            "description": "array of objects containing integer id each", 
                            "title": "atomic ids"
                        }
                    ], 
                    "title": "atomic vectors schema"
                }, 
                "name": {
                    "enum": [
                        "atomic_coordinates"
                    ]
                }
            }, 
            "description": "coordinates of atoms by ids, vector, unitless", 
            "title": "atomic coordinates"
        }
    }
}
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{
    "units": "crystal", 
    "elements": [
        {
            "id": "value"
        }
    ], 
    "name": "basis", 
    "coordinates": {
        "values": [
            {
                "id": 1, 
                "value": [
                    0, 
                    0, 
                    0
                ]
            }, 
            {
                "id": 2, 
                "value": [
                    0.25, 
                    0.25, 
                    0.25
                ]
            }
        ], 
        "name": "atomic_coordinates"
    }
}

Bravais Lattice

Lattice Bravais holds information about the three-dimensional periodic structure specified implicitly through lengths and angles between lattice vectors, and their units.

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{
    "allOf": [
        {
            "schemaId": "core-primitive-3d-lattice", 
            "required": [
                "a", 
                "b", 
                "c", 
                "alpha", 
                "beta", 
                "gamma"
            ], 
            "type": "object", 
            "properties": {
                "a": {
                    "type": "number", 
                    "description": "length of the first lattice vector"
                }, 
                "c": {
                    "type": "number", 
                    "description": "length of the third lattice vector"
                }, 
                "b": {
                    "type": "number", 
                    "description": "length of the second lattice vector"
                }, 
                "beta": {
                    "type": "number", 
                    "description": "angle between second and third lattice vector"
                }, 
                "alpha": {
                    "type": "number", 
                    "description": "angle between first and second lattice vector"
                }, 
                "gamma": {
                    "type": "number", 
                    "description": "angle between first and third lattice vector"
                }
            }, 
            "title": "3 dimensional lattice schema"
        }
    ], 
    "schemaId": "properties-directory-structural-lattice-lattice-bravais", 
    "required": [
        "type"
    ], 
    "title": "lattice implicit schema", 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "properties": {
        "units": {
            "type": "object", 
            "properties": {
                "length": {
                    "enum": [
                        "angstrom", 
                        "bohr"
                    ], 
                    "type": "string"
                }, 
                "angle": {
                    "enum": [
                        "degree", 
                        "radian"
                    ], 
                    "type": "string"
                }
            }
        }, 
        "type": {
            "enum": [
                "CUB", 
                "BCC", 
                "FCC", 
                "TET", 
                "MCL", 
                "ORC", 
                "ORCC", 
                "ORCF", 
                "ORCI", 
                "HEX", 
                "BCT", 
                "TRI", 
                "MCLC", 
                "RHL"
            ], 
            "type": "string", 
            "description": "Bravais lattice type in short notation"
        }
    }
}
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{
    "a": 5.14, 
    "c": 5.14, 
    "b": 5.14, 
    "beta": 90.0, 
    "units": {
        "length": "angstrom", 
        "angle": "degree"
    }, 
    "alpha": 90.0, 
    "type": "CUB", 
    "gamma": 90.0
}

Lattice Vectors

Lattice vectors holds information about the three-dimensional periodic structure explicitly, by specifying the three lattice vectors and their units.

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{
    "schemaId": "properties-directory-structural-lattice-lattice-vectors", 
    "allOf": [
        {
            "schemaId": "core-abstract-3d-vector-basis", 
            "required": [
                "a", 
                "b", 
                "c"
            ], 
            "type": "object", 
            "properties": {
                "a": {
                    "description": "first vector", 
                    "title": "array of 3 number elements schema", 
                    "minItems": 3, 
                    "items": {
                        "type": "number"
                    }, 
                    "schemaId": "core-primitive-array-of-3-numbers", 
                    "maxItems": 3, 
                    "type": "array"
                }, 
                "c": {
                    "description": "third vector", 
                    "title": "array of 3 number elements schema", 
                    "minItems": 3, 
                    "items": {
                        "type": "number"
                    }, 
                    "schemaId": "core-primitive-array-of-3-numbers", 
                    "maxItems": 3, 
                    "type": "array"
                }, 
                "b": {
                    "description": "second vector", 
                    "title": "array of 3 number elements schema", 
                    "minItems": 3, 
                    "items": {
                        "type": "number"
                    }, 
                    "schemaId": "core-primitive-array-of-3-numbers", 
                    "maxItems": 3, 
                    "type": "array"
                }
            }, 
            "title": "3 dimensional vector basis"
        }
    ], 
    "properties": {
        "units": {
            "enum": [
                "km", 
                "m", 
                "pm", 
                "nm", 
                "angstrom", 
                "a.u.", 
                "bohr", 
                "fractional", 
                "crystal", 
                "cartesian", 
                "alat"
            ]
        }, 
        "alat": {
            "default": 1.0, 
            "type": "number", 
            "description": "lattice parameter for fractional coordinates"
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "lattice explicit unit"
}
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{
    "a": [
        5.0, 
        0.000121312, 
        0.000131415
    ], 
    "units": "angstrom", 
    "c": [
        0.000121313, 
        0.000121312, 
        5.0
    ], 
    "b": [
        0.000121312, 
        5.0, 
        0.000121314
    ], 
    "alat": 1.0
}

Density

The Density of the material is defined by the sum of the atomic masses within the unit cell, divided by its volume.

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{
    "schemaId": "properties-directory-structural-density", 
    "allOf": [
        {
            "schemaId": "core-primitive-scalar", 
            "required": [
                "value"
            ], 
            "type": "object", 
            "properties": {
                "value": {
                    "type": "number"
                }
            }, 
            "title": "scalar schema"
        }
    ], 
    "properties": {
        "units": {
            "enum": [
                "g/cm^3"
            ]
        }, 
        "name": {
            "enum": [
                "density"
            ]
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "density schema"
}
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{
    "units": "g/cm^3", 
    "name": "density", 
    "value": 2.33
}

Elemental Ratio

The elemental ratio is given by the fraction of all atoms in a crystal which are composed of a certain element.

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{
    "description": "ration of this element in the compound", 
    "allOf": [
        {
            "schemaId": "core-primitive-scalar", 
            "required": [
                "value"
            ], 
            "type": "object", 
            "properties": {
                "value": {
                    "type": "number"
                }
            }, 
            "title": "scalar schema"
        }
    ], 
    "schemaId": "properties-directory-structural-elemental-ratio", 
    "title": "elemental-ratio", 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "properties": {
        "name": {
            "enum": [
                "elemental_ratio"
            ]
        }, 
        "value": {
            "max": 1, 
            "min": 0
        }, 
        "element": {
            "type": "string", 
            "description": "the element this ratio is for"
        }
    }
}
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{
    "name": "elemental_ratio", 
    "value": 0.71, 
    "element": "Si"
}

Magnetic Moments

The magnetic moment of ferromagnetic materials can also be computed.

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{
    "schemaId": "properties-directory-structural-magnetic-moments", 
    "description": "magnetization on each ion", 
    "properties": {
        "units": {
            "enum": [
                "uB"
            ]
        }, 
        "values": {
            "items": {
                "properties": {
                    "value": {
                        "schemaId": "core-abstract-vector", 
                        "anyOf": [
                            {
                                "title": "array of 3 number elements schema", 
                                "minItems": 3, 
                                "items": {
                                    "type": "number"
                                }, 
                                "schemaId": "core-primitive-array-of-3-numbers", 
                                "maxItems": 3, 
                                "type": "array"
                            }, 
                            {
                                "title": "array of 3 boolean elements schema", 
                                "minItems": 3, 
                                "items": {
                                    "type": "boolean"
                                }, 
                                "schemaId": "core-primitive-array-of-3-booleans", 
                                "maxItems": 3, 
                                "type": "array"
                            }
                        ], 
                        "title": "vector schema"
                    }
                }
            }, 
            "schemaId": "core-reusable-atomic-vectors", 
            "allOf": [
                {
                    "items": {
                        "uniqueItems": true, 
                        "type": "object", 
                        "properties": {
                            "id": {
                                "type": "integer", 
                                "description": "integer id of this entry"
                            }
                        }
                    }, 
                    "schemaId": "core-primitive-array-of-ids", 
                    "type": "array", 
                    "description": "array of objects containing integer id each", 
                    "title": "atomic ids"
                }
            ], 
            "title": "atomic vectors schema"
        }, 
        "name": {
            "enum": [
                "magnetic_moments"
            ]
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "magnetic moments"
}
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{
    "units": "uB", 
    "values": [
        {
            "id": 1, 
            "value": [
                0.0, 
                0.0, 
                1.235
            ]
        }, 
        {
            "id": 2, 
            "value": [
                0.0, 
                0.0, 
                -1.235
            ]
        }
    ], 
    "name": "magnetic_moments"
}

P Norm

The P norm measures how homogeneous a material is in terms of its chemical composition.

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{
    "description": "https://en.wikipedia.org/wiki/Norm_(mathematics)#p-norm", 
    "allOf": [
        {
            "schemaId": "core-primitive-scalar", 
            "required": [
                "value"
            ], 
            "type": "object", 
            "properties": {
                "value": {
                    "type": "number"
                }
            }, 
            "title": "scalar schema"
        }
    ], 
    "schemaId": "properties-directory-structural-p-norm", 
    "title": "p_norm", 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "properties": {
        "name": {
            "enum": [
                "p-norm"
            ]
        }, 
        "degree": {
            "type": "integer", 
            "description": "degree of the dimensionality of the norm"
        }
    }
}
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{
    "value": 0.71, 
    "name": "p-norm", 
    "degree": 10
}

Symmetry

The Space Group of the crystal structure, indicating the symmetry elements that it contains, is also available.

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{
    "schemaId": "properties-directory-structural-symmetry", 
    "properties": {
        "tolerance": {
            "properties": {
                "units": {
                    "enum": [
                        "angstrom"
                    ]
                }
            }, 
            "description": "tolerance used for symmetry calculation", 
            "allOf": [
                {
                    "schemaId": "core-primitive-scalar", 
                    "required": [
                        "value"
                    ], 
                    "type": "object", 
                    "properties": {
                        "value": {
                            "type": "number"
                        }
                    }, 
                    "title": "scalar schema"
                }
            ]
        }, 
        "name": {
            "enum": [
                "symmetry"
            ]
        }, 
        "spaceGroupSymbol": {
            "type": "string", 
            "description": "space group symbol in Hermann\u2013Mauguin notation"
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "symmetry schema"
}
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{
    "tolerance": {
        "units": "angstrom", 
        "value": 0.3
    }, 
    "name": "symmetry", 
    "spaceGroupSymbol": "Fd-3m"
}

Volume

The volume of the unit cell is given by the scalar triple product of the lattice vectors.

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{
    "schemaId": "properties-directory-structural-volume", 
    "allOf": [
        {
            "schemaId": "core-primitive-scalar", 
            "required": [
                "value"
            ], 
            "type": "object", 
            "properties": {
                "value": {
                    "type": "number"
                }
            }, 
            "title": "scalar schema"
        }
    ], 
    "properties": {
        "units": {
            "enum": [
                "angstrom^3"
            ]
        }, 
        "name": {
            "enum": [
                "volume"
            ]
        }
    }, 
    "$schema": "http://json-schema.org/draft-04/schema#", 
    "title": "volume schema"
}
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{
    "units": "angstrom^3", 
    "name": "volume", 
    "value": 131.1
}