[Pw_forum] Band gap hybrid functionals
reffymz at gmail.com
Wed Nov 11 15:02:08 CET 2015
But I mentioned a problem with using a very dense k - point grid and an 8
atom Si cell, the program exits before it can output the forces, stresses,
and the individual contributions to the total energy (hence why regardless
of what screening parameter I used I got the same band gap, as the fock).
Nobody was able to point me in the right direction with that. Also, another
user has previously reported that using a 2 atom si cell results in an
oscillation in the total energy as you increase ecutwfc (something I have
also verified), so I'm not sure I can accurately calculate the band gap
using a 2 atom cell either.
On 11 November 2015 at 12:18, Ref Fymz <reffymz at gmail.com> wrote:
> Thanks for the reply. So if I use an 8 atom Si cell, and use fixed
> occupations with 32 bands, the difference between the highest occupied and
> lowest unoccupied is my actual band gap? (i.e the one I can compare to PBE
> and experiment)
> On 11 November 2015 at 10:13, Ref Fymz <reffymz at gmail.com> wrote:
>> I've tried searching the forum, and I haven't come across a way to
>> calculate the band gap in a material using the hybrid functionals. I know
>> you can't do nscf calculations, but is there any simple way to calculate
>> the band gap for a material using scf simulations?
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