[QE-users] Hubbard U+V for a large system

[Johannes Meusburger - STFC UKRI]

Dear Andriii,

As far as I know, the default settings limit DFT + U + V to 50 atoms. However, this should be readily adjusted by changing the natx parameter in the Modules/parameters.f90 (Modules/parameters.f90 · develop · QEF - Quantum Espresso Foundation / q-e · GitLab<https://gitlab.com/QEF/q-e/-/blob/develop/Modules/parameters.f90>) to your system size.

Also, having a look at your input file I do not think that you should Hubbard_U(3) = 1d-10  AND Hubbard_V(3,3,1), since Hubbard_V(3,3,1) already refers to the on-site Hubbard U for atom 3.  To sum up, if you are using DFT + U use Hubbard_U, if you are using DFT + U + V just use the Hubbard_V keyword.

The solutions to both of these problems are well described in the pw.x  input description (pw.x: input description (quantum-espresso.org)<https://www.quantum-espresso.org/Doc/INPUT_PW.html#idm471>, hence I thought you might find it helpful to give it a read. Also, I highly recommend working your way through the examples on the QE github page (q-e/LiCoO2.scf.in at master · QEF/q-e · GitHub<https://github.com/QEF/q-e/blob/master/HP/examples/example10/reference/LiCoO2.scf.in>).

HTH,

Johannes Meusburger
ISIS Neutron and Muon Source & Diamond Light Source & University of Exeter, UK
________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Andrii Shyichuk via users <users at lists.quantum-espresso.org>
Sent: Wednesday, October 13, 2021 8:52 PM
To: users at lists.quantum-espresso.org <users at lists.quantum-espresso.org>
Subject: [QE-users] Hubbard U+V for a large system

Dear Users,

I'm trying to run a DFT+U+V Hubbard parameters calculation (hp.x) on a
system with 80 atoms.

SCF run is fine, file hp.x run gives:

Index of the second rotated atom=           0
      Error in routine symonpair (1):
      Out of bounds

How can the second rotated atom be zero?

My input is based on the YouTube "Tutorial on DFT+U+V using Quantum
ESPRESSO (v6.7)".
The +U+V settings are:
                    lda_plus_u = .true.
               lda_plus_u_kind = 2
                  Hubbard_U(3) = 1d-10
              Hubbard_V(1,1,1) = 1d-10
              Hubbard_V(2,2,1) = 1d-10
              Hubbard_V(3,3,1) = 1d-10
              Hubbard_V(4,4,1) = 1d-10
              ...
              Hubbard_V(80,80,1) = 1d-10

Is it a bug, or is it just the question of some parameter tweaking?
I've already increased natx to 150.

Thank you.
Andrii Shyichuk, University of Wrocław.
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