This page explains how to calculate and visualize the electronic density mesh for FCC Silicon.

Create job

Si is the default material, so if you choose "Create a Job" from the sidebar on the home page Si will automatically be loaded.

Choose workflow

Under "Workflow" tab chose the "Electronic Density Mesh" for Quantum Espresso. In addition, for electronic properties with a non-self consistent step it is critical to have a high k-point density to give enough detail to calculate an accurate band structure.

For VASP the workflow for "Electronic Density Mesh" is simpler and just one unit that produces a file called CHGCAR.

Adjust kpoints

For charge density it is critical to have a high k-point density to properly visualize charge isosurfaces. The second unit is a post-processing unit to generate the file for visualization. We set the kpoint density to 11x11x11 in the first workflow unit.

Submit job

Before submitting the calculation, click on the "Compute" tab and examine the compute parameters. This is a small structure so 1 CPU and 5 minutes are sufficient. Click "No" when asked if you want to save a duplicate material.

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 execution's sub-tab.

Checking results

Once the calculation is complete, under the Results tab at the bottom of the page there will be a listing of the files and directories on the system that is clickable to download and transit directories. The screen shots below show the location of the charge density file

For Quantum ESPRESSO:

For VASP:

VASP CHGCAR

Preparing for visualization

When all 5 units are complete we are ready to go to the terminal window to visualize the electron density mesh. The next step is to open a Remote Desktop Connection to the terminal so that you can run graphical interface programs for visualization. Underneath the "Terminal" option in the right sidebar you used earlier in the tutorial is a "Remote Desktop" option.

Remote Desktop

Remote desktop

Select this and a different overlay will appear in your web browser of a graphical user session.

Start Remote Desktop

Next steps depend on the simulation engine used

Quantum ESPRESSO

Open XCrysden

Find and open XCrysden under "Applications" > "Other" dropdown menu item.

Other->XCrysden

Visualize charge density

Within XCrysden, go to "File" > "Open" and navigate to the directory where the electron density file is and open to a visualization of the electron density.

If you used the default project for this calculation, then the location will be: /home/<your username>/data/<your username>/<job name>/

Adjust the value of charge density to be displayed and toggle the isosurface buttons to display the data.

VASP

Open Vesta

Find and open Vesta under the "Other" dropdown menu item.

Other->Vesta

Visualize charge density

Within Vesta, go to file->Open and navigate to the directory where the electron density file (CHGCAR) is and open to a visualization of the electron density.

If you used the default project for this calculation, then the location will be: /home/<your username>/data/<your username>/<job name>/

Open CHGCAR File

Your results should look similar to the image below:

Visualize CHGCAR