12: Benzene — Valence and low-lying conduction states¶

Valence States¶

Outline: Obtain MLWFs for the valence states of benzene
Directory: tutorials/tutorial12/ Files can be downloaded from here
Input Files
- benzene.scf The pwscf input file for ground state calculation
- benzene.pw2wan Input file for pw2wannier90
- benzene.win The wannier90 input file
Run pwscf to obtain the ground state of benzene
Terminal
```
pw.x < benzene.scf > scf.out
```
Run wannier90 to generate a list of the required overlaps (written into the benzene.nnkp file).
Terminal
```
wannier90.x -pp benzene
```
Run pw2wannier90 to compute the overlap between Bloch states and the projections for the starting guess (written in the benzene.mmn and benzene.amn files).
Terminal
```
pw2wannier90.x < benzene.pw2wan > pw2wan.out
```
Run wannier90 to compute the MLWFs.
Terminal
```
wannier90.x benzene
```

Inspect the output file benzene.wout. The total spread converges to its minimum value after just a few iterations.

Plot the MLWFs by adding the following keywords to the input file benzene.win

Input file

restart = plot
wannier_plot = true
wannier_plot_format = cube
wannier_plot_list = 2-4

and re-running wannier90. Visualise them using, e.g., XCrySDen.

Valence + Conduction States¶

Outline: Obtain MLWFs for the valence and low-lying conduction states of benzene.
Input Files
- benzene.scf The pwscf input file for ground state calculation
- benzene.nscf The pwscf input file to obtain Bloch states for the conduction states
- benzene.pw2wan Input file for pw2wannier90
- benzene.win The wannier90 input file

In order to form localised WF we use the disentanglement procedure. The position of the inner energy window is set to lie in the energy gap; the outer energy window is set to 4.0 eV. Modify the input file appropriately.

Run pwscf and wannier90.\ Inspect the output file benzene.wout. The minimisation of the spread occurs in a two-step procedure. First, we minimise \(\Omega_{\rm I}\). Then, we minimise \(\Omega_{\rm O}+\Omega_{{\rm OD}}\).
Plot the MLWFs by adding the following commands to the input file benzene.win
Input file
```
restart = plot
wannier_plot = true
wannier_plot_format = cube
wannier_plot_list = 1,7,13
```
and re-running wannier90. Visualise them using, e.g., XCrySDen.