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ISMEAR choice when LOPTICS = .TRUE.

Posted: Sat Mar 01, 2014 5:28 pm
by yjzhou
Dear VASP users,

Does anyone have the experience for calculating frequency dependent dielectric functions of a metal?

I have a metallic system and I want to calculate the dielectric functions. I do not relax the structure and not forces are needed so I guess I can use ISMEAR = -5 for better DOS and total energy calculations. But I cannot get the plasma frequency then, and the dielectric function is quite different from the result from gaussian smearing(i.e. ISMEAR =0 ) case.

My questions are then
1. Shall I expect the big difference between these two cases? Which smearing shall I use?
2. Does the epsilon(w) from OUTCAR include only interband transition contributions? Since my results from ISMEAR = -5 seem like the total effect of intraband and interband, namely it seems a drude peak exists there.


Thank you
YJ

Re: ISMEAR choice when LOPTICS = .TRUE.

Posted: Thu Sep 12, 2024 7:18 am
by support_vasp

Hi,

We're sorry that we didn’t answer your question. This does not live up to the quality of support that we aim to provide. The team has since expanded. If we can still help with your problem, please ask again in a new post, linking to this one, and we will answer as quickly as possible.

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VASP