[QE-developers] Implement a functional from libxc in QE

[Timrov Iurii]

Dear All,


> (or maybe the question was on TDDFPT?)


In TDDFPT there are already hybrids. So maybe this can be reused in DFPT for phonons? At least this could be a good starting point. Ideally, what is common between TDDFPT and DFPT should be moved to LR_Modules, which would facilitate its reuse in other linear response codes of QE.


Greetings,

Iurii


________________________________
From: developers <developers-bounces at lists.quantum-espresso.org> on behalf of Nicola Marzari <nicola.marzari at epfl.ch>
Sent: Wednesday, May 6, 2020 8:06:44 PM
To: General discussion list for Quantum ESPRESSO developers; Layla Martin-Samos
Subject: Re: [QE-developers] Implement a functional from libxc in QE



Well, transition-metal oxides can be a good example - see the work here
from the "U" gang for the phonons in CoO - major differences:
https://arxiv.org/abs/1910.06195 (paper is now published in PRB).

So, the question is when is EXX better than Hubbard, and one would want
DFPT+EXX rather than DFPT+U (that is available)? I think for localized
d/f orbitals the Hubbard approach is nicer, much less expensive, and
tuned to the actual system studied.

In something where self-interaciton is less well identifiable (say, an
oxidized thiophene where the hole is difficult to describe), well, one
could not use U and would hope that EXX helps.

                                nicola



On 06/05/2020 19:57, Layla Martin-Samos wrote:
> I am not aware of any case (material, molecule, ...) in which the
> vibrational spectra would have been so crappy with standard functionals
> (no fock) that could justify the burden of phonons with EXX
> (calculation, implementation etc...). Someone is aware of some
> application of that kind? (or maybe the question was on TDDFPT?)
>
> Layla
>
> Le mer. 6 mai 2020 à 18:58, Paolo Giannozzi <p.giannozzi at gmail.com
> <mailto:p.giannozzi at gmail.com>> a écrit :
>
>     Somebodty asked me the following question. Any comments (opther than
>     "it will be horribly slow")?
>
>      > Do you know if anyone working on implementing DFPT + hybrid
>     functionals ?
>
>     Paolo
>
>
>
>     --
>     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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--
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Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
Director, National Centre for Competence in Research NCCR MARVEL, EPFL
http://theossrv1.epfl.ch/Main/Contact http://nccr-marvel.ch/en/project
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