Mono layer and multiple layer MoS2 (Wrong tutorial)

[Hesam]

1) Is there any example or input deck which shows how to get the correct band structure of MoS2 and other TMDC materials (in mono layer and multi layer)? I saw the following tutorial which shows a wrong band gap (indirect band gap for mono layer MoS2 which should be direct)!
http://quantumwise.com/publications/tutorials/mini-tutorials/167-transmission-spectrum-of-perfect-sheets-of-graphene-and-mos2


2) How I can make a direction non-periodic or periodic? (from 3d periodic to 2d periodic )

3) If I want to relax structure, I should run the simulation twice?

[Anders Blom]

1. This is caused by the fact that we had the wrong structure in our database (cf. the release note for 13.8 and Phys. Chem. Chem. Phys. 4, 4078 (2002)). Using 13.8 (or running a geometry optimization first) produces the correct results. The tutorial is being updated - thanks for pointing it out.

2. Just add enough vacuum so there are no interactions.

3. No, that's not necessary. If you set it up in the Script Generator you can add the band structure analysis task right after the optimization. Or, if you run the optimization separately and saved it to a file "file.nc", you can use "Analysis from File" to read the optimized geometry and state from "file.nc" (most likely the optimized geometry is represented by gID001 in the NC file) and then just add the band structure analysis task which is fast.

[Hesam]

Thanks!
4) If I want to optimize the structure and run the band structure analysis in single run, how should be the order?
First bulk, second calculator, third optimizer, fourth band structure?

5) Also how I can add vacuum in VNL? Increasing cell size? how?

[Dipankar Saha]

Go to Builder...explore "BulkTools"..... there you will be finding an option "Lattice Parameters" ...where you can increase the x/ y/ z, value to increase spacing in any of the directions as per the requirement.......
____________

[Dipankar Saha]

For your other question.... I think, you have to optimize your bulk unit cell, or Device....before actually setting the method for doing the Calculations and analyses.....

[Anders Blom]

4) Correct - config, calculator, optimization, band structure.