This example illustrates how to use Quantum Espresso and postprocessing codes

- to make a contour plot in the [110] plane of the charge density for Si
- to plot the band structure of Si.

The calculation proceeds as follows (for the meaning of the cited input variables see the appropriate INPUT_* file)

- make a self-consistent calculation (input=si.scf.in, output=si.scf.out)
- run the postprocessing program pp.x (input=si.pp_rho.in, output=si.pp_rho.out) in order to extract a 2D cut of the charge density. See INPUT_PP for details of the input.
- run plotrho.x program (input=si.plotrho.in, output=si.plotrho.out) in order to produce a postscript file: si.rho.ps.
- make a non self-consistent calculation including more bands (nbnd=8). (input=si.band.in, output=si.band.out)
- run program bands.x that extracts the eigenvalues, tries to determine the correct crossing (based on the character of the bands), writes bands to a file (sibands.dat). (input=si.bands.in, output=si.bands.out)
- run program plotband.x that reads the file produced by bands.x and produces a postscript plot file (sibands.ps)

## Results

## Software Used

### Quantum Espresso

Quantum ESPRESSO is an integrated suite of computer codes for electronic-structure calculations and materials modeling at the nanoscale. It is based on density-functional theory, plane waves, and pseudopotentials. Quantum ESPRESSO has evolved into a distribution of independent and inter-operable codes. The Quantum ESPRESSO distribution consists of a “historical” core set of components, and a set of plug-ins that perform more advanced tasks, plus a number of third-party packages designed to be inter-operable with the core components.

For more details see Quantum Espresso .

## Related Models

Following are some related models available for cloning/copying by anyone: