[Q-e-developers] on the calculation of Hubbard U values
José Carlos Conesa
jcconesa at icp.csic.es
Fri Oct 13 10:53:49 CEST 2017
Dear all,
I fully understand Timrov's concern about the available
pseudopotentials, I was not aware of that problem. What I would suggest
then, if a well tested qe 6.2 version is to be released very soon, is to
include in those .f90 files just all elements for which no problem
exists, and leave for a later version a better handling of this issue.
All the best,
El 13/10/2017 a las 10:44, Timrov Iurii escribió:
>
> Dear All,
>
>
> There were some discussions outside of the QE developers mailing list
> about this issue, and we would like to share with you our thoughts.
> José proposed his changes to the files set_hubbard_l.f90,
> set_hubbard_n.f90, tabd.f90, where all elements (we haven't checked
> that really all) are tabulated with the corresponding channel to
> be effected by the Hubbard correction. We think we should not hurry
> and not include this in QE 6.2 which is going to be released very soon
> (as far as we know).
>
>
> The main problem is that some pseudos may not comply with the default
> choice of states made in the aforementioned routines. For example, for
> La, in José's version of set_hubbard_l.f90, it is specified that
> hubbard_l = 3 (i.e. the f state). While some pseudos include empty 4f
> states (e.g. Pslibrary, GBRV), some pseudos do not (e.g. Dojo library,
> La.pbe-nsp-van.UPF from the QE web site). So, in the latter case the
> code will crash because the f channel is not present in the pseudo.
> Thus, we have to be careful. As Paolo and we discussed, it
> is probably better to have a possibility to specify hubbard_l from
> the input (e.g. if you choose the pseudo which contains 4f for La and
> you want to apply a Hubbard correction to 4f, and not 5d, then just
> specify hubbard_l = 3 from the input; if nothing is specified in the
> input, the code can use the default value which should work for all
> pseudos, e.g. hubbard_l =2 for La). Another option might be to keep as
> the default hubbard_l = 3 for La, and if the code does not find the f
> state in the pseudo then stop smoothly and ask the user to change
> hubbard_l by specifying it in the input. As we said, probably it would
> be safer to implement this things after the release of QE 6.2 in order
> to avoid possible bugs.
>
>
> Best regards,
>
> Iurii and Matteo
>
>
> Swiss Federal Institute of Technology Lausanne (EPFL)
> Laboratory of Theory and Simulation of Materials (THEOS)
> CH-1015 Lausanne, Switzerland
> +41 21 69 34 881
>
> ------------------------------------------------------------------------
> *From:* q-e-developers-bounces at qe-forge.org
> <q-e-developers-bounces at qe-forge.org> on behalf of Paolo Giannozzi
> <p.giannozzi at gmail.com>
> *Sent:* Thursday, October 12, 2017 7:20 PM
> *To:* General discussion list for Quantum ESPRESSO developers
> *Cc:* jcconesa at icp.csic.es
> *Subject:* Re: [Q-e-developers] on the calculation of Hubbard U values
> I also think that a better solution would be providing parameters of
> Hubbard U from input. Something like a "Hubbard_U" card with
> Mn(3d)=4.0
> O(2p)=5.0
> ...
>
> Paolo
>
> On Thu, Oct 12, 2017 at 1:50 PM, Timrov Iurii <iurii.timrov at epfl.ch
> <mailto:iurii.timrov at epfl.ch>> wrote:
>
> Dear Jose,
>
>
> Thanks for the remark, we will keep this in mind when working on
> the porting of the DFpT code to compute U to the official release
> of QE. Perhaps it would be useful to introduce input variables
> which allow user to specify which atomic manifold to associate
> with the Hubbard correction.
>
>
> Best regards,
>
> Iurii
>
>
> --
> Dr. Iurii Timrov
> Postdoctoral Researcher
> Swiss Federal Institute of Technology Lausanne (EPFL)
> Laboratory of Theory and Simulation of Materials (THEOS)
> CH-1015 Lausanne, Switzerland
> +41 21 69 34 881
> http://people.epfl.ch/265334
> ------------------------------------------------------------------------
> *From:* q-e-developers-bounces at qe-forge.org
> <mailto:q-e-developers-bounces at qe-forge.org>
> <q-e-developers-bounces at qe-forge.org
> <mailto:q-e-developers-bounces at qe-forge.org>> on behalf of José C.
> Conesa <jcconesa at icp.csic.es <mailto:jcconesa at icp.csic.es>>
> *Sent:* Thursday, October 12, 2017 1:29 PM
> *To:* q-e-developers at qe-forge.org <mailto:q-e-developers at qe-forge.org>
> *Subject:* [Q-e-developers] on the calculation of Hubbard U values
>
> Dear QE developers,
>
> I have seen in the last Psi-K highlight about the advances in the
> QE code that version 6.2 (now at a release candidate status) will
> allow computing ab initio U values for the DFT+U scheme using
> DFpT, so that supercells would not be needed and the process would
> be much easier. Then, if one wants to find U values considering
> the responsenot only for a specific element but for all of them
> present in the material, i.e. computing the complete (inverse)
> susceptibility matrices, it is necessary that Hubbard parameters
> be considered for all elements in the material. But in its present
> version, the code in files Modules/set_hubbard_l.f90
> Modules/set_hubbard_n.f90 and PW/src/tabd.f90 only allows using
> Hubbard parameters for part of the elements in the periodic table.
>
> For this reason I wish to make you a request: please include in
> those files, in the final qe-6.2 version, all elements in the
> periodic table (well, you may omit noble gases) so that each user
> does not need to modify those files, and compile the executables
> again, every time that (s)he has to consider a new element in the
> material for which U values should be computed. This should not be
> difficult to do. I am aware that in some cases it may be not clear
> which atomic subshell should be affected by the Hubbard
> correction; for example, La might need to do it for d or f
> orbitals depending on the compound, and In or Zn might be in a
> similar problem for p and d orbitals. This could be solved just by
> adding a word of caution in the manual.
>
> Hoping that this modification may be made,
>
> Best wishes,
>
> --
> José C. Conesa
> Instituto de Catálisis y Petroleoquímica, CSIC
> Marie Curie 2, Cantoblanco
> 28049 Madrid, Spain
> Tel.(+34)915854766 <tel:+34%20915%2085%2047%2066>
>
>
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>
>
>
>
> --
> 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
>
--
José C. Conesa
Director
Instituto de Catálisis y Petroleoquímica, CSIC
Marie Curie 2, Madrid, Spain
www.icp.csic.es
Tel. (+34)915854766
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