ISMEAR choice when LOPTICS = .TRUE.
Posted: Sat Mar 01, 2014 5:28 pm
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
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