[QE-users] Some inconsistency between QE-6.7MaX and current QE-7.1
Mahmoud Payami Shabestari
mpayami at aeoi.org.ir
Fri Sep 23 11:44:07 CEST 2022
Dear Iurii,
Many thanks for your detailed explanation. I am convinced.
Best regards,
Mahmoud
From: Iurii TIMROV <iurii.timrov at epfl.ch>
To: Mahmoud Payami Shabestari <mpayami at aeoi.org.ir>, "Quantum ESPRESSO users
Forum" <users at lists.quantum-espresso.org>, Paolo Giannozzi
<paolo.giannozzi at uniud.it>
Date: Fri, 23 Sep 2022 09:35:42 +0000
Subject: Re: [QE-users] Some inconsistency between QE-6.7MaX and current
QE-7.1
> If one would compare "DFT+U+ortho-atomic" with the "orbital-dependent HSE"
method, can one be certain that the latter is still much more
computationally expensive than the former?
It depends on the system size. Some comparison between DFT+U (with
first-principles and self-consistent U using ortho-atomic orbitals) and
HSE06 is made in the Appendix B of this paper:
https://www.mdpi.com/2076-3417/11/5/2395
Accuracy of DFT+U vs HSE06: in DFT+U, the U parameter can be computed for
each system at hand while in HSE06 the fraction of exact exchange is 0.25
for all systems. When people tune the fraction of exact exchange in HSE it
is no longer first principles (though there are various methods how to
compute it - some references are mentioned in the intro of the paper above).
Therefore, it is not only about the speed/scaling but also about the
accuracy.
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: Mahmoud Payami Shabestari <mpayami at aeoi.org.ir>
Sent: Friday, September 23, 2022 11:26:33 AM
To: Iurii TIMROV; Quantum ESPRESSO users Forum; Paolo Giannozzi
Subject: Re: [QE-users] Some inconsistency between QE-6.7MaX and current
QE-7.1
Dear Iurii,
Thank you for yor reply and referencing the relevant paper.
Now the important question:
people prefer DFT+U, because in principle the computational cost is of order
(not so larger) than that of DFT, because one just introduces a correction
from "APPROXIMATE" Hubbard Model on DFT.
If one would compare "DFT+U+ortho-atomic" with the "orbital-dependent HSE"
method, can one be certain that the latter is still much more
computationally expensive than the former?
Thank you in advance.
Bests,
Mahmoud
From: Iurii TIMROV via users <users at lists.quantum-espresso.org>
To: Paolo Giannozzi <paolo.giannozzi at uniud.it>, Mahmoud Payami Shabestari
<mpayami at aeoi.org.ir>, Quantum ESPRESSO users Forum
<users at lists.quantum-espresso.org>
Date: Fri, 23 Sep 2022 07:37:57 +0000
Subject: Re: [QE-users] Some inconsistency between QE-6.7MaX and current
QE-7.1
Hubbard forces and stresses using "ortho-atomic" Hubbard projectors are much
more expensive than with "atomic". It is explained in PRB 102, 235159
(2020). Computational scaling is discussed in the appendix C.
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: users <users-bounces at lists.quantum-espresso.org> on behalf of Mahmoud
Payami Shabestari via users <users at lists.quantum-espresso.org>
Sent: Thursday, September 22, 2022 9:03:17 PM
To: Paolo Giannozzi; Quantum ESPRESSO users Forum
Subject: Re: [QE-users] Some inconsistency between QE-6.7MaX and current
QE-7.1
Dear Paolo,
Thank you so much for your comments.
Actually, to find some sense about the time needed to calculate force, I
have performed scf calculations for just one iteration, but different
numbers of atoms (4, 8, 12, 16, 32, 48, 64, 80, 96, 108) with more or less
the sama number of k points in BZ. The supercells were generated from the
QE-7.1/PW/example08 unitcell. The inputs and outputs are uploaded in:
https://drive.google.com/drive/folders/12cWLR7PkMI1wolxgRLnOSCi4IhtnLmEO?usp=sharing
The results for low number of atoms seems to take reasonable times, but for
larger ones the time to calculate force becomes larger than the time for
just one iteration.
Do you see any un-normal behavior in force calculation routine?
Thank you very much for your comments.
Bests, Mahmoud
From: Paolo Giannozzi <paolo.giannozzi at uniud.it>
To: Mahmoud Payami Shabestari <mpayami at aeoi.org.ir>, Quantum ESPRESSO users
Forum <users at lists.quantum-espresso.org>
Date: Thu, 22 Sep 2022 18:18:51 +0200
Subject: Re: [QE-users] Some inconsistency between QE-6.7MaX and current
QE-7.1
Not sure what you mean exactly. As a rule of thumb, the calculation of
the Hubbard contribution to forces should take no more than 1/3 or 1/4,
likely much less than that, of the time needed for a scf calculation, at
least for the simple ("atomic") U projection.
Paolo
On 21/09/2022 19:31, Mahmoud Payami Shabestari via users wrote:
> Dear Paolo,
> Thank you so much for the comment on automatic parallelization.
> On the second issue, how can one estimate the execution time for force
> calculation as a function of number of Hubbard levels in a DFT+U
> calculation with ortho-atomic U_projection?
> Thank you in advance.
> Bests,
> Mahmoud
>
> From: Paolo Giannozzi <paolo.giannozzi at uniud.it>
> To: users at lists.quantum-espresso.org
> Date: Tue, 20 Sep 2022 07:58:42 +0200
> Subject: Re: [QE-users] Some inconsistency between QE-6.7MaX and
> current QE-7.1
> The optimization you are referring to is actually an automatic choice
of
> parallelization option, but it is not used if you explicitly specify
the
> parallelization options (e.g. with -nk N -nd M). For the original
> problem: one has to see under which exact coonditions it happens
>
> Paolo
>
> On 20/09/2022 05:01, Mahmoud Payami Shabestari via users wrote:
> > Dear QE Developers,
> > Hi.
> > Kindly, when I use the same scf input for QE-6.7MaX and QE-7.1, the
> > results of forces on atoms are more or less similar but with a
small
> > difference. However, the calculated pressures are
> SIGNIFICANTLY_DIFFERENT.
> > Secondly, when the number of atoms is of order say 50, the
> calculation
> > of forces on atoms using QE-7.1 is VERY VERY time consuming.
> > In the release note of QE7.1 one feature mentioned is an
"automatic"
> > optimizations for accelerating the calculations.
> > Could it happen that in some cases instead of optimizations one
> > encounters with deceleration?
> > How can one disable this automatic optimization?
> > Thank you in advance.
> > With Best Regards,
> > Mahmoud Payami
> > NSTRI, AEOI, Tehran, Iran
> > Email: mpayami at aeoi.org.ir <mailto:mpayami%40aeoi.org.ir>
> > Phone: +98 (0)21 82066504
> > --------------------------------------------------------
> >
> > _______________________________________________
> > The Quantum ESPRESSO community stands by the Ukrainian
> > people and expresses its concerns about the devastating
> > effects that the Russian military offensive has on their
> > country and on the free and peaceful scientific, cultural,
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> > _______________________________________________
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> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
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> _______________________________________________
> The Quantum ESPRESSO community stands by the Ukrainian
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> The Quantum ESPRESSO community stands by the Ukrainian
> people and expresses its concerns about the devastating
> effects that the Russian military offensive has on their
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> and economic cooperation amongst peoples
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
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--
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Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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