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This page explains how to calculate formation energy [1] based on density functional theory [2]. We will be studying copper oxide CuO2 and use VASP [3] as our simulation engine.

Pre-calculated energy values for defautl pseudopotentials

Formation energy requires the knowledge of the total and zero point energies of constituents in their standard state. We have pre-calculated these values at a converged k-point density for all supported pseudopotentials. These values are automatically populated to eliminate the need to recalculate them again.

Import Material

Click on "Create a Job" from left-hand sidebar on the home page. Si will automatically be loaded as it is the default material. The formation energy of elements is zero, so for this test case we will need to import CuO2 structure.

To import CuO2 use sidebar again, and select the "Materials" page. Then click the cloud button on the upper right of that page to initiate import. In the search box, put CuO2 and after a few seconds, the entries for CuO2 from materialsproject.org will appear.

Choose the version of CuO2 with the lowest formation energy and click on it. Then click on the right side of the entry to bring up the option to import the material

Create job

Now that you have imported CuO2 we are ready to use that structure to reproduce formation energy calculation. Click "Create Job" link again. If you go to the "Choose A Material" section of the page, and click on the drop-down menu, CuO2 should be one of your options to select as the material for the simulation.

Choose workflow

Next go to the workflow tab and select "Formation Energy" as the workflow type. The units displayed as part of this workflow will look similar to a combination of the kpt-convergence and relaxation tutorials, but will include a couple of extra units after the vc_relax unit used to obtain the elements total and zero point energies and calculate the formation energy.

Submit job

This calculation will take some time to complete due to both k-point convergence and relaxation being run on a relatively large supercell. It's important to adjust the computation parameters accordingly. Click on the "Compute" tab and increase the maximum run time limit to 30 minutes and the number of cores to 4. Also click on your username in the box to turn on email notifications about the jobs status.

Monitor status

As each unit in the workflow is executing, you can monitor its progress live by viewing both the output of the executable as well as a graphical representation of the total energy convergence on the "Status" tab under each unit's sub-tab.

Check results

When the execution of all unitls finished, switching to the Results tab and the sub-tab for the final execution unit will have an entry titled "Formation Energy" that will display formation energy of the material. The more negative the value, the more stable the material is. This "Formation Energy" box will also show the energetic parameters (total energy and zero-point energy) for constituent elements used to calculate the property.

  1. Formation Energy, Wikipedia
  2. Density Functional Theory, Wikipedia
  3. Vienna ab-inito simulation package, Website