On Tue 08 Mar 2011, Marci wrote: > Hi Roberto, > > Why do you use that huge smearing (3000K)? Are you sure you need it? Hi Marton, I used a high (actually 3000K = 0.25 eV, not so high compared to the gap=1.1eV) temperature in order to be able to overcome eventual local potential minima during the relaxation. > Given the small gap, your system behaves like a metal right now. The gap is 1.1 eV, why you say it's small? > If I were you I would try to reduce it to let's say 30K so there are no > more fractional occupations. I followed you suggestion and it worked (attached). Thank you very much. I didn't considered that parameter. But also I really didn't expected such a dependence: the fermi level was at half gap! But in principle you're right: some of the conduction bands become occupied and the sum on the transitions is performed between occupied-unoccupied bands, and therefore at the end also "intraband" transitions become considered. Right? Roberto > Marton > > -- > PhD student > Department of Atomic Physics > Budapest University of Technology and Economics > > On Tue, Mar 8, 2011 at 11:45 AM, Roberto Guerra <[email protected]> wrote: > > Hello, > > > > noone of the developers is interested in such a fundamental issue? It > > may be a bug... > > > > RG > > > > On Mon 07 Mar 2011, you wrote: > >> Dear all, > >> > >> I repeated the calculation using a 2x2x2 grid (input file attached). > >> The result is the same. This is not surprising, since the problem is > >> not related, in my opinion, to the calculation accuracy (also, the > >> calculation at the gamma point should be reasonable for an amorphous > >> system). > >> > >> I verified that the Fermi energy lies inside the gap (bands > >> attached). > >> > >> The epsimg is larger than zero at E<Egap. That's not possible. > >> > >> > >> Roberto > >> > >> In date 5/3/11 23:52:32, Alexander Vozny wrote: > >> > Roberto, > >> > are you sure your Fermi level is in the gap? > >> > If yes, then I would agree with Karim that most likely your k-grid > >> > for DOS is different from k-grid for optical calculation. > >> > Alexander. > >> > >> In date 4/3/11 18:40:44, karim rezouali wrote: > >> > Roberto, > >> > > >> > The band structure appears not to be totally correct. Seeing your > >> > input file systlab.fdf, I realized that this curve is obtained > >> > under the gamma point.approximation > >> > > >> > Try to sample the Brillouin zone as follows: > >> > %block kgrid_Monkhorst_Pack > >> > 2 0 0 0.0 > >> > 0 2 0 0.0 > >> > 0 0 2 0.0 > >> > %endblock kgrid_Monkhorst_Pack > >> > > >> > > >> > Optical calculations: > >> > > >> > %block Optical.Mesh > >> > > >> > 2 2 2 > >> > > >> > %endblock Optical.Mesh > >> > > >> > These changes will make the calculation slightly heavier but that's > >> > the price to pay for something more accurate.
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