Messages

1

General Questions and Answers / Re: Non-self-consistent and Equivalent bulk

« on: December 16, 2017, 23:31 »

If the Fermi level is not in the middle of the band gap, that is usually because the number of k-points is too low. Please make sure k-points etc. are converged - it will improve the quality of your results.

I'd check that, thanks very much.

2

General Questions and Answers / Re: Non-self-consistent and Equivalent bulk

« on: December 16, 2017, 06:12 »

I have looked into it, and the current writing is correct.

Point 1. refers to the fact that you can define the IterationControlParameters for the Equivalent Bulk calculation itself, and those are not allowed to include NonSelfConsistent, which means that the EquivalentBulk calculation itself must be self-consistent - otherwise it would essentially just be the same as NeutralAtom.

However, point 2. refers to the fact that you can do a non-selfconsistent calculation, using the result of the EquivalentBulk calculation as the starting point.

Did that clear things up for you?

Appreciated, I am convinced by that.

Can I ask one additional question that, does it matter if the Fermi level of the calculated electron transmission spectrum is NOT in the middle (at 0 eV energy) of of the conduction band minimum and valence band maximum, provided that I've set energy zero parameter as "Average Fermi level", with which the Fermi level is supposed to be in the middle. And what do you think would cause this?

Thank you very much.

3

General Questions and Answers / Re: Non-self-consistent and Equivalent bulk

« on: December 14, 2017, 05:35 »

You are right, there seems to be an inconsistency there - I will look into it.

However, point 3. is a tutorial for a very old version of ATK, so that is no longer relevant. Tutorials not on docs.quantumwise.com should be considered obsolete unless you use a quite old version of VNL/ATK.

Hi, sir, thanks for reply and investigation.
yes, that's an old version, and I'm now using version 2016.4.

4

General Questions and Answers / Non-self-consistent and Equivalent bulk

« on: December 13, 2017, 00:47 »

Hello, Sir,

I feel confused about descriptions which seem to contradict with each other as follows.

1. It says "It is not allowed to use NonSelfConsistent for EquivalentBulk."
(https://docs.quantumwise.com/manuals/Types/EquivalentBulk/EquivalentBulk.html)
2. It also writes "Setup a non-self-consistent calculation with an equivalent bulk initial density."
(https://docs.quantumwise.com/manuals/Types/DeviceAlgorithmParameters/DeviceAlgorithmParameters.html)
3. There seems a calculation done with "non-self-consistent with equivalent bulk initial density".
(http://quantumwise.com/documents/tutorials/ATK-11.8/BasicGrapheneTutorial/index.html/chap.zigzag_transport.html#sect2.zigzag.equiv_bulk)

Would you please elaborate a bit about this ?
Thank you very much.

5

General Questions and Answers / Re: Double counting in combined sw and tersoff potential

« on: September 21, 2017, 11:26 »

I think this section describes almost exactly what you want to do, but maybe I misunderstand your problem: https://docs.quantumwise.com/tutorials/combining_potentials/combining_potentials.html#combining-a-tersoff-and-a-lennard-jones-potential

You should be able to follow that procedure, and then simply omit the Si-Si terms from the Tersoff potential.

Dear Sir, Would you please tell how to omit the Si-Si terms in Tersoff while keeping that in SW potential ?
Thank you very much.

6

General Questions and Answers / Re: Double counting in combined sw and tersoff potential

« on: September 11, 2017, 09:38 »

Hi, Sir,
  Thank you very much for your prompt reply.
   Unfortunately I failed to find something pertinent to my problem above there (maybe I missed it, though).
   Like what I did in LAMMPS, I simply set parameters for si-si-si interaction in SiO-tersoff to zero, then I get no double-counting for Si interaction, and only Si-sw works for it. I just want to do the same thing here in QW otherwise I get double-counting.

7

General Questions and Answers / Double counting in combined sw and tersoff potential

« on: September 11, 2017, 07:43 »

Hi, all,
  I have a Silicon structure with Silica (amorphous) inside. I want to use Si-sw potential for Silicon atoms (all Si atoms including those in Silica) and SiO2-tersoff potential for Silica (only the part for Si-O interaction). Now if I combine both potentials in the phonon transmission calculation, the Silicon interaction will be double counted by both sw ans tersoff, is there a way of turning off the Silicon interaction in tersoff potential so that only sw potential works for it ?
  I appreciate any suggestions from you, thanks a lot !