[Pw_forum] hybrid functional

Tue Apr 9 15:10:29 CEST 2013

Dear Arles,
thanks for your answer. My doubts are about the employment of the 
projwfc.x, post processing tool, when using hybrid functional,  since 
the README of the hybrid functional tutorial says that one gets into 
troubles when performing non-scf calculations. At the moment I see the 
way to proceed if I wish to plot the band structure from the log file of 
the scf run, but i do not know how to get informations about the dos 
from such file, since it (as far as I understand) seems to be the only 
run i can perform when employing hybrid functionals. Do you know how to 
get informations about the dos from the .log of a scf run?
Thank you!!!
Valentina

Il 04/09/2013 02:24 PM, Arles V. Gil Rebaza ha scritto:
> Dear Valentina,
> Yes, projwfc.x is a postprocessing tool like dos.x, whether you want 
> to get only the density of state, "dos.x" is enough, whereas 
> "projwfc.x" you can obtain DOS, projected DOS (PDOS) and the magnetic 
> moment per atom too.
> http://www.quantum-espresso.org/?page_id=876
>
> Best
>
> PhD Arles V. Gil Rebaza
> Instituto de Física de La Plata
> Argentina
>
>
> 2013/4/9 "Valentina Dellacà C.R.F. S.C.p.A." 
> <valentina.dellaca at tirocinanti.crf.it 
> <mailto:valentina.dellaca at tirocinanti.crf.it>>
>
>     Dear Mohnish,
>     thanks for you answer. I will follow your suggestion and try also
>     HSE, with a coarser k-point mesh, (indeed with PBE0 the
>     computation time is quiet large), and I did not know about projwfc.x.
>     I have a further question concerning the DOS. If I wish to know
>     about the DOS of my system, which uses  the hybrid functional
>     implementation, am I able to use the projwfc.x? Is'n it a
>     postprocessing tool?
>     Thanks,
>     regards,
>     Valentina
>
>     Il 04/09/2013 11:18 AM, mohnish pandey ha scritto:
>>     Hi,
>>
>>     As far as I can understand there is no rule. It depends how fine
>>     you want to represent your Fock operator. Normally calculations
>>     of the Fock exchange in expensive, so its not affordable to do
>>     very fine grid calculations  So I suggest you start with low
>>     nqx(1, 2, 3) and increase it systematically. Increasing it will
>>     give you better results( I mean converged results, not
>>     necessarily close to experiments).
>>
>>     Just an advice, PBE0 needs much more high density k-point mesh
>>     for the convergence of Fock exchange since it's a long range
>>     interaction. So you have to do calculations with high density of
>>     k-points. But if you use HSE instead of PBE0 you get away with
>>     coarser k-point mesh since it involves screened exchange
>>     interaction which converges much faster than bare Coulomb
>>     exchange as in PBE0. Regarding to the DOS plot you will find a
>>     nice tutorial on Heither's website, I am pasting the link
>>     http://www.stanford.edu/~hkulik/www/Tutorials/Entries/2012/1/24_Population_analysis_and_PDOS.html
>>     <http://www.stanford.edu/%7Ehkulik/www/Tutorials/Entries/2012/1/24_Population_analysis_and_PDOS.html>
>>
>>
>>     On Tue, Apr 9, 2013 at 10:05 AM, "Valentina Dellacà C.R.F.
>>     S.C.p.A." <valentina.dellaca at tirocinanti.crf.it
>>     <mailto:valentina.dellaca at tirocinanti.crf.it>> wrote:
>>
>>         Hi,
>>         I am a Quantum Espresso beginner user, and I am simulating
>>         the Ta2O5 structure, with the employment of the hybrid
>>         functional PBE0. I have some questions :
>>
>>         - if I choose a k-point grid not in automatic, how should I
>>         pick the nqx1,2,3? Is there a rule?
>>         - when one wishes to have informations (ex. plot) about the
>>         density of states from the scf run, how should I proceed?
>>
>>         Thank you,
>>         regards
>>         Valentina
>>>
>>>         -- 
>>
>>
>>         -- 
>>
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>>
>>
>>
>>     -- 
>>     Regards,
>>     MOHNISH,
>>     -----------------------------------------------------------------
>>     Mohnish Pandey,
>>     PhD Student,
>>     Center for Atomic Scale Materials Design,
>>     Department of Physics,
>>     Technical University of Denmark
>>     -----------------------------------------------------------------
>
>
>     -- 
>
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> -- 
> ###--------->   Arles V. <---------###

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