[QE-users] Advice on HP for a PBA material

[Timrov, Iurii]

Dear Krystian,

My colleague Eric Macke (University of Bremen) has been working extensively on PBAs using the HP code. I asked him to get in touch with you and address your questions.


  *
There are also some more theoretical questions relating to the HP code. For example, while I appreciate that the entire DFPT reformulation in terms of monochromatic perturbations allows us to avoid the need for supercells of sizes matching the perturbation wavelengths, I do not quite understand why the aforementioned paper uses a supercell composed of 8 formula units for LiMn2O4?


The reason is that we wanted to impose a certain magnetic ordering that required that supercell.


  *
Is it generally desirable to use cells with orthogonal lattice vectors with HP?

No. The code is general and does not have any restrictions in this sense.

HTH

Greetings,
Iurii

----------------------------------------------------------
Dr. Iurii TIMROV
Tenure-track scientist
Laboratory for Materials Simulations (LMS)
Paul Scherrer Institute (PSI)
CH-5232 Villigen, Switzerland
Profile: www.psi.ch/en/lms/people/iurii-timrov<https://www.psi.ch/en/lms/people/iurii-timrov>
Group website: www.timrovresearch.com/<https://www.timrovresearch.com/>
________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Krystian Gierczak <krystian.gierczak at chem.ox.ac.uk>
Sent: Friday, May 22, 2026 14:36
To: users at lists.quantum-espresso.org <users at lists.quantum-espresso.org>
Subject: [QE-users] Advice on HP for a PBA material

Dear QE users,

I hope this email finds you well.

I am currently trying to compute the Hubbard U parameters for the Mn[Fe(CN)6] material with the HP code.

I am following the standard workflow from the HP examples as well as the procedure from the Phys. Chem. Chem. Phys., 2023,  25, 9061-9072 article by Dr Timrov.

My procedure is as follows:

  1.
vc-relax,
  2.
fake-metal SCF,
  3.
insulator SCF,
  4.
hp.x

But then, I get a pair of U values that seem chemically counterintuitive, i.e., chemically I would expect my high-spin Mn(III) to have a larger U value than my low-spin Fe(III). Interestingly, this is not at all what I get from hp.x.

Please find the inputs and outputs attached. I have omitted the vc-relax output as it is quite a heavy file.

Please, would you be able to advise on whether I am doing something wrong?

There are also some more theoretical questions relating to the HP code. For example, while I appreciate that the entire DFPT reformulation in terms of monochromatic perturbations allows us to avoid the need for supercells of sizes matching the perturbation wavelengths, I do not quite understand why the aforementioned paper uses a supercell composed of 8 formula units for LiMn2O4? Is it generally desirable to use cells with orthogonal lattice vectors with HP?


Many thanks in advance for your help.

Best wishes,

Krystian

Krystian A. Gierczak
PhD Student in the VLD Group,
Department of Chemistry, University of Oxford
Web: https://deringer.chem.ox.ac.uk

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