[Pw_forum] Empty bands with hybrid functional

[Paolo Giannozzi]

On Tue, 2013-12-03 at 12:22 -0800, Alexandr Fonari wrote:

> What is the right way to get empty bands when employing hybrid functional, either:
> 
> a. First run SCF with no empty bands and then again SCF with:
>     restart_mode='restart'
>     nbnd = occupied_plus_empty_bands

unlikely to work, for a stupid reason: when restarting, the code expects
nbnd bands, and this is larger than the number of written bands

> or b. Run SCF with no empty bands and then NSCF with:
>     nbnd = occupied_plus_empty_bands

I am not sure it works, and even if it does, not sure it takes less 
time than c.) below. The diagonalization at fixed potential should
include a fixed exchange potential as well. Not sure this is done.

> or c. I've missed something and there is other way.

c. run a SCF calculation with some more empty bands. Wasteful but safe.

P.
> 
> thanks a lot,
> Alexandr Fonari,
> grad student,
> Georgia Tech.
> 
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-- 
Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222