Germanium bandgap correction

[asanchez]

Hi all,

What is the strategy when dealing with a material like Ge which DFT predicts to be metallic? r_setup reports the system as metallic and for the case of Ge, HF corrections (which usually overestimate the bandgap, right?) still report the system to be metallic.

Thanks for your help

EDIT:

Sorry if this has already been covered before, but I haven't found anything related to this.

Also, I'm not including any specifics of the calculation because I'm just interested in knowing if there's a special procedure one should follow in these cases where DFT mistakenly predicts a metallic behaviour so yambo will know that it's not supposed to be a metal.

[Daniele Varsano]

Dear Alfonso,
in general in this cases, a self consistent procedures should be needed (GW, HF, COHSEX etc..) in order to have a qualitatively correct starting point. SC calculations are implemented in Yambo, bust they are note yet released in the GPL distribution.
Anyway according to previous calculations, see. e.g. here:
http://journals.aps.org/prb/pdf/10.1103 ... .69.125212
Self energy corrections should be enough to open the gap and have the correct positions of the bands.

Best,
Daniele

[asanchez]

Thanks Daniele