[Wien] Confusion about DOS

shamik chakrabarti shamik15041981 at gmail.com
Sat Nov 27 16:22:39 CET 2021


Dear Prof. Blaha,

                 I have 56 atoms supercell & it is converged with one
k-point. In this regard should I do the following;
(1) save_lapw case_1kpoint
(2) run_kgenhf_lapw   for 4 kpoints
(3) x lapw1 -hf -up
(4) x lapw1 -hf -dn
(5) x lapw2 -hf -qtl -up
(6) x lapw2 -hf -qtl -dn
(7) x tetra -hf -up
(8) x tetra -hf -dn

Looking forward to hearing from you.

with regards,


On Sat, 27 Nov 2021 at 20:40, Peter Blaha <pblaha at theochem.tuwien.ac.at>
wrote:

> >     Is this a calculation with just one k-point ?
> >
> > Yes. It is a calculation with one k point
>
> Then everything is clear.
>
> Obviously, with one k-point in the BZ one cannot use the tetrahedra
> method. There are no bands (E as funktion of k), but just one eigenvalue
> "per band". In principle, your DOS consists of a number of
> delta-functions. So tetra switches automatically to a broadening method
> (Gaussian by default) with some broadening (see description of tetra and
> case.int in UG).
> With a broadening method of course also your VBM (CBM) will be broadened
> and this is what you see in the DOS.
>
> Of course, a single k-point calculation is valid only for very large
> supercells....
>
> >
> >
> >     look into case.outputt
> >
> >
> > Near Fermi Energy:
> > case.outputtup:  0.00086   664.55  40.0000     0.37   0.0208
> > case.outputtdn:  0.00886   851.95  46.0000     0.28   0.0244
> >
> >
> >     These are data without broadening and you should see how many
> electrons
> >     (integral of DOS, 3rd column) are up to EF.
> >
> >     In addition, check out the :BAND  ranges in scf2
> >     You should see a correspondence of those with the DOS (in Ry).
> >
> >     There are 217 bands
> >
> >   Looking forward to your response.
> >
> > with regards,
> >
> >
> >     Am 27.11.2021 um 14:08 schrieb shamik chakrabarti:
> >      > Yes, the gap 2.875 eV is the value found from SCF. I have tried
> with
> >      > broadening 0.001 & also with 0.000...however, it shows no
> >     improvement.
> >      > Is it due to numerical noise & can be neglected?
> >      >
> >      > On Sat, 27 Nov 2021 at 18:30, Tran, Fabien
> >     <fabien.tran at tuwien.ac.at <mailto:fabien.tran at tuwien.ac.at>
> >      > <mailto:fabien.tran at tuwien.ac.at
> >     <mailto:fabien.tran at tuwien.ac.at>>> wrote:
> >      >
> >      >     Is 2.875 eV the value of :GAP in case.scf? If yes, it looks
> >     like if
> >      >     the Fermi energy
> >      >     is not placed correctly on the DOS, because the gap between
> the
> >      >     valence and
> >      >     conduction band seems to be close to 2.875 eV.
> >      >     Could it be due to the broadening in case.int
> >     <http://case.int> <http://case.int <http://case.int>>? Try
> >      >     to execute tetra with a reduced (or no) broadening.
> >      >
> >      >     ________________________________________
> >      >     From: Wien <wien-bounces at zeus.theochem.tuwien.ac.at
> >     <mailto:wien-bounces at zeus.theochem.tuwien.ac.at>
> >      >     <mailto:wien-bounces at zeus.theochem.tuwien.ac.at
> >     <mailto:wien-bounces at zeus.theochem.tuwien.ac.at>>> on behalf of
> >      >     shamik chakrabarti <shamik15041981 at gmail.com
> >     <mailto:shamik15041981 at gmail.com>
> >      >     <mailto:shamik15041981 at gmail.com
> >     <mailto:shamik15041981 at gmail.com>>>
> >      >     Sent: Saturday, November 27, 2021 7:54 AM
> >      >     To: A Mailing list for WIEN2k users
> >      >     Subject: [Wien] Confusion about DOS
> >      >
> >      >     Dear Wien2k users,
> >      >
> >      >                         I have plotted DOS for material with
> >     converged
> >      >     SCF using HSE06. I got a bandgap of 2,875 eV. However, in the
> >      >     plotted DOS it can be seen that a small amount of DOS from the
> >      >     valence band is crossing the Fermi energy. I have attached
> >     the plot
> >      >     to this mail.
> >      >
> >      >     Is this crossing can be neglected or I should have to change
> some
> >      >     other parameters like broadening etc.
> >      >
> >      >     with regards,
> >      >
> >      >     --
> >      >     Dr. Shamik Chakrabarti
> >      >     Research Fellow
> >      >     Department of Physics
> >      >     Indian Institute of Technology Patna
> >      >     Bihta-801103
> >      >     Patna
> >      >     Bihar, India
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> >      >
> >      >
> >      > --
> >      > Dr. Shamik Chakrabarti
> >      > Research Fellow
> >      > Department of Physics
> >      > Indian Institute of Technology Patna
> >      > Bihta-801103
> >      > Patna
> >      > Bihar, India
> >      >
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> >
> >     --
> >
>  --------------------------------------------------------------------------
> >     Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> >     Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
> >     Email: blaha at theochem.tuwien.ac.at
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> >
> >
> > --
> > Dr. Shamik Chakrabarti
> > Research Fellow
> > Department of Physics
> > Indian Institute of Technology Patna
> > Bihta-801103
> > Patna
> > Bihar, India
> >
> > _______________________________________________
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> --
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
> Email: blaha at theochem.tuwien.ac.at    WIEN2k: http://www.wien2k.at
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-- 
Dr. Shamik Chakrabarti
Research Fellow
Department of Physics
Indian Institute of Technology Patna
Bihta-801103
Patna
Bihar, India
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