QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: Jahanzaib on June 26, 2023, 17:23

Title: Kpoints vs DOS
Post by: Jahanzaib on June 26, 2023, 17:23

Dear Expert
I am really confused about the issue I am facing that I calculated DOS for my system with different K points (1,3,5,7 in C direction and A=B=1) and got the exactly same energy in every case.

- the way I do - I optimized my geometry in first step
- I given the path of optimized geometry, then calculated the DOS to perform convergences test.

I studied online and nothing found something more relavent to my problem - just got "The energy *will* be the same if your system only has localised states, for example a molecule in a large simulation cell".

For the reference, I have attached optimized file and then DOS with 1 kpoints. Can some one suggest me what's the issue and why I am getting the same energy?

Title: Re: Kpoints vs DOS
Post by: Jahanzaib on June 28, 2023, 02:59

I think my structure is symmetrical that may play a role in obtaining the same energy for different k-points. 
- I already optimized the geometry, is there a way I can put symmetrical=False in DOS.

or some one guide me from my previous post.

Thank you

Title: Re: Kpoints vs DOS
Post by: Anders Blom on June 29, 2023, 21:55

The reason why your results are not dependent on the number k-points is simply that it's so large in the periodic direction. The longer the periodicity is, the fewer k-points you need, this is a general point.

You should not use this keyword for DOS.