Dear Iurii, I'll have a look into the source code to see if I can spot anything there.
I suspect the only other cause of this could be that the calculation were run on two different machines (ARCHER2 vs CSD3) although I can't see obviously why it would cause this specific problem. In any case, I'll double check by running the full set of calculations on each machine and seeing if it seems reproducible. Thank you! Theo Weinberger PhD Student University of Cambridge From: Iurii Timrov <iurii.tim...@epfl.ch> Sent: Tuesday, September 12, 2023 10:46 AM To: Theo Weinberger <ti...@cam.ac.uk>; Quantum ESPRESSO users Forum <users@lists.quantum-espresso.org> Subject: Re: Spin counting in hp.x with paramagnetic metals Dear Theo, Thanks for clarifications! > I am typically looking at pressure-induced structural transitions in systems > with complex magnetic ground states. However, in some cases the exact > magnetic configurations are unknown and so to simplify the problem (and since > these structural transitions occur at high temperature in the paramagnetic > state) I have been trying to perform the calculations in the nonmagnetic > state. It is in these instances where I see this approximate doubling of U: > i.e. when I allow the system to relax into a FM ordered state (with nspin=2) > before using hp.x the value of U ends up being around half that of when I > don't include spin effects (nspin=1). I have not seen anything like that. You can have a closer look in to the HP code and report if you find any bugs. But I would need to understand better your system in order to figure out what is happening. In general terms it is hard to say anything more specific. Regards, 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: Theo Weinberger <ti...@cam.ac.uk<mailto:ti...@cam.ac.uk>> Sent: Tuesday, September 12, 2023 11:41:04 AM To: Iurii Timrov; Quantum ESPRESSO users Forum Subject: RE: Spin counting in hp.x with paramagnetic metals Dear Iurii, Yes, to be more precise I mean that when I am looking at these systems, I am modelling them as being nonmagnetic and so I was wondering whether it was the spin degeneracy that was causing this difference. I am typically looking at pressure-induced structural transitions in systems with complex magnetic ground states. However, in some cases the exact magnetic configurations are unknown and so to simplify the problem (and since these structural transitions occur at high temperature in the paramagnetic state) I have been trying to perform the calculations in the nonmagnetic state. It is in these instances where I see this approximate doubling of U: i.e. when I allow the system to relax into a FM ordered state (with nspin=2) before using hp.x the value of U ends up being around half that of when I don't include spin effects (nspin=1). I hope this clarifies what I have been seeing. Best wishes, Theo Weinberger PhD Student University of Cambridge From: users <users-boun...@lists.quantum-espresso.org<mailto:users-boun...@lists.quantum-espresso.org>> On Behalf Of Iurii Timrov via users Sent: Tuesday, September 12, 2023 10:31 AM To: users@lists.quantum-espresso.org<mailto:users@lists.quantum-espresso.org> Subject: Re: [QE-users] Spin counting in hp.x with paramagnetic metals Dear Theo, How do you model the paramagnetic state? Please note that "paramagnetic" and "nonmagnetic" state is not the same thing. For nonmagnetic calculations there is a factor of 2 due to spin degeneracy when computing sums over electronic states (i.e. in charge density, occupation matrix, and other quantities). If you take a nonmagnetic material (e.g. LiCoO2) and model it as a spin-polarized system (nspin=2), the value of U will be the same as when modeling it as nonmagetic (because the magnetization will be zero). So I do not understand why do you have a factor of 2 difference for U in your simulations. Greetings, 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-boun...@lists.quantum-espresso.org<mailto:users-boun...@lists.quantum-espresso.org>> on behalf of Theo Weinberger <ti...@cam.ac.uk<mailto:ti...@cam.ac.uk>> Sent: Tuesday, September 12, 2023 11:21:03 AM To: users@lists.quantum-espresso.org<mailto:users@lists.quantum-espresso.org> Subject: [QE-users] Spin counting in hp.x with paramagnetic metals Dear Quantum Espresso Users, I have been using the hp.x code to calculate the Hubbard-U corrections for correlated metallic systems in both their spin-polarised and paramagnetic states. In several materials I have noticed that the Hubbard-U value determined for a material in its paramagnetic ground state is approximately twice that compared to when a spin-polarised ground state is assumed (with all other parameters kept the same). I was wondering whether anyone had any insight into how the accounting for spins in occupied Hubbard states works for the hp.x code and whether the paramagnetic implementation of hp.x perhaps counts all spins states twice resulting in this larger value. Thank you in advance, Theo Weinberger PhD Student University of Cambridge
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