[Q-e-developers] on the calculation of Hubbard U values

[Timrov Iurii]

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 <q-e-developers-bounces at qe-forge.org> on behalf of José C. Conesa <jcconesa at icp.csic.es>
Sent: Thursday, October 12, 2017 1:29 PM
To: 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 response not 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
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