Dear Thomas,
> especially the parenthesis - I can somehow understand the problem; I guess it
> has to do with the possibility to properly project onto the "localized"
> subspace, but do you know if there is a more rigorous explanation, maybe a
> publication? Or Iurii? Maybe in one of your papers?
No, I am not aware of any publication where this is discussed. I do not think
this is discussed anywhere, it is just a technicality (how things are
implemented).
Regarding the parenthesis: In the older versions of QE (before the new
DFT+Hubbard syntax introduced in v7.1), the code was considering in some
routines the last "L channel" (where L is the orbital quantum number) as the
Hubbard channel. But since v7.1 there is no this logic for DFT+U and DFT+U+V
("atomic" and "ortho-atomic" projectors), because now the user has to specify
in the input N and L (where N is the principal quantum number), so there is no
ambiguity. I presume (but I am not sure) that this might be the reason why
there is a problem for the "pseudo" type of Hubbard projectors (i.e. the same
projectors as in VASP) when there are also semicore states (so you have the
same L twice).
Greetings,
Iurii
--
Dr. Iurii TIMROV
Senior Research Scientist
Theory and Simulation of Materials (THEOS)
Swiss Federal Institute of Technology Lausanne (EPFL)
CH-1015 Lausanne, Switzerland
+41 21 69 34 881
http://people.epfl.ch/265334
________________________________
From: Thomas Brumme <[email protected]>
Sent: Friday, December 9, 2022 11:18:47 PM
To: Paolo Giannozzi; [email protected]
Cc: Iurii TIMROV
Subject: AW: [QE-users] DFT+U - error when using the pseudopotential projectors
Thanks Paolo for this important information - I haven't had the time yet to
look at the code itself.
Concerning this small info:
one might run into troubles when using a PP with semicore states with same l as
valence states
(also otherwhere for DFT+Hubbard)
especially the parenthesis - I can somehow understand the problem; I guess it
has to do with the
possibility to properly project onto the "localized" subspace, but do you know
if there is a more
rigorous explanation, maybe a publication? Or Iurii? Maybe in one of your
papers?
Kind regards
Thomas
--
Dr. rer. nat. Thomas Brumme
Theoretical chemistry
TU Dresden - KOE / 103
Bergstr. 66c
01069 Dresden
Tel: +49 (0)351 463 40844
email: [email protected]
________________________________
Von: Paolo Giannozzi <[email protected]>
Gesendet: Freitag, 9. Dezember 2022 17:06
An: [email protected]
Cc: Brumme, Thomas; Iurii TIMROV
Betreff: Re: [QE-users] DFT+U - error when using the pseudopotential projectors
On 07/12/2022 16:26, Iurii TIMROV via users wrote:
> it might be that something has been broken over the years
it might be, given the complete absence of tests and examples for that
feature. It isn't, though: with a different pseudopotential
(Co.pbesol-n-kjpaw_psl.1.0.0.UPF) not containing semi-core states,
neither the current code nor the first version (5.0.3) implementing
DFT+U with pseudopotential projectors crash. The results seem to be the
same (convergence is nasty as usual so it is difficult to get exactly
the same numbers).
A comment in PW/src/init_q_aeps.f90 seems to confirm that the problem is
in the logic used to choose the projectors:
! NOTE: one might run into troubles when using a PP with semicore
! states with same l as valence states (also otherwhere for DFT+Hubbard
Paolo
--
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 206, 33100 Udine Italy, +39-0432-558216
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