Discussion:
[Pw_forum] LDA+U or GGA+U?
GAO Zhe
2012-03-12 11:21:30 UTC
Permalink
Dear QE developer and users:
I just began to try LDA+U method in QE, by adding lda_plus_u = .true. and Hubbard_U(i) parameters to scf input file, where the U value was determined by following M.Cococcioni's thesis and Prof. Marzari's paper (PRL, 97, 103001).
However, when I check other code about this area, I found these days they are using GGA+U as well. Such like in VASP, I saw they mentioned in forum that LDA or GGA is just depends on XC in pseudo-potential. And in the case of Abinit, the official example is calculated by PBE-PAW pseudo-potential.
Therefore, I am wondering that, if I setted lda_plus_u = .true. and used GGA pseudo-potential, may I say I am using GGA+U method? Since when I tried in that way, I saw the output is as:
LDA+U calculation, Hubbard_lmax = 2
atomic species L Hubbard U Hubbard alpha
Any suggestion is welcome. Thanks.

--
GAO Zhe
CMC Lab, Materials Science & Engineering Department,
Seoul National University, South Korea

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Lorenzo Paulatto
2012-03-12 11:29:34 UTC
Permalink
Post by GAO Zhe
Therefore, I am wondering that, if I setted lda_plus_u = .true. and used
GGA pseudo-potential, may I say I am using GGA+U method?
Yes, you may. The +U correction can be applied to any kind of functional.
The "lda" in "lda+U" is just a name, it does not imply that the functional
has to be strictly local.

best regards
--
Lorenzo Paulatto IdR @ IMPMC/CNRS & Universit? Paris 6
phone: +33 (0)1 44275 084 / skype: paulatz
www: http://www-int.impmc.upmc.fr/~paulatto/
mail: 23-24/4?16 Bo?te courrier 115, 4 place Jussieu 75252 Paris C?dex 05
Abdeslam HOUARI
2012-03-12 16:16:42 UTC
Permalink
Dear GAO Zhe;
As told by Lorenzo Paulatto, I think that LDA+U is just a name and all the
important thing is how to include the Hubbard "U" term. However, in may
opinion, this still being true only for DFT (LDA or GGA) XC functional, and
one should take care if the XC functional is a Hybrid-type one (HF like
exchange, EXX ...etc).. I hope I'm right about this !!!


==============================================
Abdesalem HOUARI
-------------------------------------------------------------------------------------------
Department of physics, Theoretical Physics Laboratory
University of Bejaia-06000. Algeria.
E-mail: abdeslam.houari at univ-bejaia.dz<http://fr.mc274.mail.yahoo.com/mc/compose?to=abdeslam.houari at univ-bejaia.dz>&
habdeslam at gmail.com<http://fr.mc274.mail.yahoo.com/mc/compose?to=habdslam at yahoo.fr>
https://sites.google.com/site/houariabdeslam/homepage
===============================================


2012/3/12 GAO Zhe <flux_ray12 at 163.com>
Post by GAO Zhe
I just began to try LDA+U method in QE, by adding lda_plus_u = .true. and
Hubbard_U(i) parameters to scf input file, where the U value was determined
by following M.Cococcioni's thesis and Prof. Marzari's paper (PRL, 97,
103001).
However, when I check other code about this area, I found these days they
are using GGA+U as well. Such like in VASP, I saw they mentioned in forum
that LDA or GGA is just depends on XC in pseudo-potential. And in the case
of Abinit, the official example is calculated by PBE-PAW pseudo-potential.
Therefore, I am wondering that, if I setted lda_plus_u = .true. and used
GGA pseudo-potential, may I say I am using GGA+U method? Since when I tried
LDA+U calculation, Hubbard_lmax = 2
atomic species L Hubbard U Hubbard alpha
Any suggestion is welcome. Thanks.
--
GAO Zhe
CMC Lab, Materials Science & Engineering Department,
Seoul National University, South Korea
_______________________________________________
Pw_forum mailing list
Pw_forum at pwscf.org
http://www.democritos.it/mailman/listinfo/pw_forum
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GAO Zhe
2012-03-12 11:21:30 UTC
Permalink
Dear QE developer and users:
I just began to try LDA+U method in QE, by adding lda_plus_u = .true. and Hubbard_U(i) parameters to scf input file, where the U value was determined by following M.Cococcioni's thesis and Prof. Marzari's paper (PRL, 97, 103001).
However, when I check other code about this area, I found these days they are using GGA+U as well. Such like in VASP, I saw they mentioned in forum that LDA or GGA is just depends on XC in pseudo-potential. And in the case of Abinit, the official example is calculated by PBE-PAW pseudo-potential.
Therefore, I am wondering that, if I setted lda_plus_u = .true. and used GGA pseudo-potential, may I say I am using GGA+U method? Since when I tried in that way, I saw the output is as:
LDA+U calculation, Hubbard_lmax = 2
atomic species L Hubbard U Hubbard alpha
Any suggestion is welcome. Thanks.

--
GAO Zhe
CMC Lab, Materials Science & Engineering Department,
Seoul National University, South Korea

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Lorenzo Paulatto
2012-03-12 11:29:34 UTC
Permalink
Post by GAO Zhe
Therefore, I am wondering that, if I setted lda_plus_u = .true. and used
GGA pseudo-potential, may I say I am using GGA+U method?
Yes, you may. The +U correction can be applied to any kind of functional.
The "lda" in "lda+U" is just a name, it does not imply that the functional
has to be strictly local.

best regards
--
Lorenzo Paulatto IdR @ IMPMC/CNRS & Universit? Paris 6
phone: +33 (0)1 44275 084 / skype: paulatz
www: http://www-int.impmc.upmc.fr/~paulatto/
mail: 23-24/4?16 Bo?te courrier 115, 4 place Jussieu 75252 Paris C?dex 05
Abdeslam HOUARI
2012-03-12 16:16:42 UTC
Permalink
Dear GAO Zhe;
As told by Lorenzo Paulatto, I think that LDA+U is just a name and all the
important thing is how to include the Hubbard "U" term. However, in may
opinion, this still being true only for DFT (LDA or GGA) XC functional, and
one should take care if the XC functional is a Hybrid-type one (HF like
exchange, EXX ...etc).. I hope I'm right about this !!!


==============================================
Abdesalem HOUARI
-------------------------------------------------------------------------------------------
Department of physics, Theoretical Physics Laboratory
University of Bejaia-06000. Algeria.
E-mail: abdeslam.houari at univ-bejaia.dz<http://fr.mc274.mail.yahoo.com/mc/compose?to=abdeslam.houari at univ-bejaia.dz>&
habdeslam at gmail.com<http://fr.mc274.mail.yahoo.com/mc/compose?to=habdslam at yahoo.fr>
https://sites.google.com/site/houariabdeslam/homepage
===============================================


2012/3/12 GAO Zhe <flux_ray12 at 163.com>
Post by GAO Zhe
I just began to try LDA+U method in QE, by adding lda_plus_u = .true. and
Hubbard_U(i) parameters to scf input file, where the U value was determined
by following M.Cococcioni's thesis and Prof. Marzari's paper (PRL, 97,
103001).
However, when I check other code about this area, I found these days they
are using GGA+U as well. Such like in VASP, I saw they mentioned in forum
that LDA or GGA is just depends on XC in pseudo-potential. And in the case
of Abinit, the official example is calculated by PBE-PAW pseudo-potential.
Therefore, I am wondering that, if I setted lda_plus_u = .true. and used
GGA pseudo-potential, may I say I am using GGA+U method? Since when I tried
LDA+U calculation, Hubbard_lmax = 2
atomic species L Hubbard U Hubbard alpha
Any suggestion is welcome. Thanks.
--
GAO Zhe
CMC Lab, Materials Science & Engineering Department,
Seoul National University, South Korea
_______________________________________________
Pw_forum mailing list
Pw_forum at pwscf.org
http://www.democritos.it/mailman/listinfo/pw_forum
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