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.
<<attachment: a-Si_2x2x3_epsimg.png>>
<<attachment: a-Si_2x2x2_bands.png>>
rilassa.fdf
Description: application/vnd.fdf
