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Partial charge densities in VASP

Posted: Fri Sep 25, 2020 2:56 pm
by madhu_menon2
Hi,
I am trying to calculate partial charge densities. I went to the topic: wiki/index.php/LORBIT
I see that due to the issues with version >=5.4.4, they suggest the following steps:
1. Self-consistent calculation with symmetry switched on (ISYM=2)
2. Recalculation of the partial charge density with symmetry switched off (ISYM=0)
What do I calculate in step 1? I.e., what output am I looking for? Do I calculate DOS in step 1 or just the optimization? Then what do I take from step 1 as input into step 2? Obviously, I am assuming that I calculate DOS in step 2. Do I also copy CONTCAR to POSCAR in step2. Your help would be greatly appreciated. Thanks.

Re: Partial charge densities in VASP

Posted: Tue Sep 29, 2020 3:01 pm
by henrique_miranda
Hi,

All the input files for step 1 + the resulting WAVECAR need to be transfered to step 2.
If you are doing a relaxation calculation then you should do it before doing step 1.
You should start the step 1 already with the relaxed ionic positions.
Hope this answers your question.

Re: Partial charge densities in VASP

Posted: Wed Sep 30, 2020 11:57 pm
by madhu_menon2
Thanks for the suggestion. So, I should do a static calculation with ISYM=2 in step 1 and use the resulting WAVECAR as the input along with ISYM=0 to calculate the partial charges in step 2, right?

Re: Partial charge densities in VASP

Posted: Thu Oct 01, 2020 7:50 am
by henrique_miranda
Yes, that should do the trick.
I also recommend that you carefully check the partial densities that you obtain in both step 1 and 2.
The two steps are only needed because of a bug in the symmetrization of the partial densities so at least you should check that the two steps indeed yield different results.
The issue should have been fixed in VASP6

Re: Partial charge densities in VASP

Posted: Thu Oct 01, 2020 9:37 pm
by madhu_menon2
Great. Thank you! :)