[QE-developers] Matrix Elements of the Momentum Operator

[Paolo Giannozzi]

Actually It seems to me that Ef is always computed in the scf case, so I
don't see how it can be zero

Paolo

On Thu, Jan 23, 2020 at 10:11 AM Lorenzo Paulatto <paulatz at gmail.com> wrote:

> would it make sense to set Ef to the HOMO (which is always computed in
> insulators) in this case ?
>
> CALL get_homo_lumo (ehomo, elumo)
>
> On 23/01/2020 10:01, Paolo Giannozzi wrote:
> > Thank you for reporting this. As far as I know, during a band
> > calculation the Fermi energy is not computed. It is however read from
> > file (the one produced by the previous scf calculation) and re-written
> > to file at the end of the band calculation. A zero (not set) Fermi
> > energy means that it wasn't computed during the scf calculation. This
> > happens if you do not use smearing.
> >
> > There was however a bug with units: Ef was written to file in Hartree
> > a.u. but not converted to Rydberg a.u. when read. This was fixed a few
> > days ago.
> >
> > Paolo
> >
> >
> >
> > On Thu, Jan 23, 2020 at 7:30 AM Rafal Korlacki <rkorlacki2 at unl.edu
> > <mailto:rkorlacki2 at unl.edu>> wrote:
> >
> >     Hello,____
> >
> >     __ __
> >
> >     I believe there is a bug in the routine write_p_avg in all the
> >     versions 6 of QE. Specifically, in the following fragment: ____
> >
> >     __ __
> >
> >           !____
> >
> >           !   Compute the number of occupated bands at this k point____
> >
> >           !____
> >
> >           DO ibnd = 1, nbnd____
> >
> >              IF (et (ibnd, ik)<=ef) nbnd_occ = ibnd____
> >
> >           ENDDO____
> >
> >     __ __
> >
> >     It seems that the variable ef=0 rather than whatever the right
> >     number is, and the code gets confused about which bands are occupied
> >     and which are not. If I replace ef with a number corresponding to an
> >     energy somewhere within the bandgap for a particular material, the
> >     output is consistent with earlier versions of QE, like 5.3.0.
> >     Otherwise the code calculates overlaps between the wrong band pairs,
> >     the format of the output varies between k-points, etc. I tested this
> >     behavior for QE 6.2 to 6.5.____
> >
> >     __ __
> >
> >     Best regards,____
> >
> >     __ __
> >
> >     Rafal Korlacki____
> >
> >     University of Nebraska-Lincoln____
> >
> >     __ __
> >
> >     __ __
> >
> >     __ __
> >
> >     __ __
> >
> >     __ __
> >
> >     __ __
> >
> >     _______________________________________________
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> >
> >
> >
> > --
> > Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
> > Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> > Phone +39-0432-558216, fax +39-0432-558222
> >
> >
> > _______________________________________________
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> >
>
> --
> Lorenzo Paulatto - Paris
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>


-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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