Dear Robert, Please have a look at this paper: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.103.045141
Yes, generally, one should also redo the vc-relax calculations using updated U and V values using DFT+U+V. But if, for example, one wants to work with the fixed geometry (e.g. the experimental one), then obviously there is no need to do the vc-relax calculations. Greetings, Iurii ---------------------------------------------------------- Dr. Iurii TIMROV Tenure-track scientist Laboratory for Materials Simulations (LMS) Paul Scherrer Institut (PSI) CH-5232 Villigen, Switzerland +41 56 310 62 14 https://www.psi.ch/en/lms/people/iurii-timrov ________________________________ From: users <[email protected]> on behalf of ROBERT MIKHAIL GUZMAN ARELLANO via users <[email protected]> Sent: Thursday, September 26, 2024 17:34 To: [email protected] <[email protected]> Subject: [QE-users] It is neccesary to make a vc-relax in each DFT U+V calculation? Dear members, I am starting to work in DFT U+V making calculations with pw.x and hp.x of Quantum Espresso package. So my question is: In order to calculate the U and V values with hp.x. What is the path to follow? At his time. I am doing these steps. 0. Calibrate pseudo potentials, k-points, and frequency of waves and density. 1. Calculate the crystalline structure using vc-relax. 2. Make a scf calculation using the best atomic positions and unit cell parameters obtained in vc-relax calculation. In this calculation, I put a small value of U and V between orbitals. (1.d-3 eV) 3 run hp.x in order to calculate better values of U and V. 4 extract the U and V values calculated by hp.x, and put these in a new scf calculation and run the last. 5 repeat the 3 step and after the 4 step until the U and V values between 2 different calculations look equal or with small difference (0.01eV). My Question is: is it necessary to make a vc-relax between the 3 and 4 steps? I looked at some examples which do that in order to calculate U value,but do not do the same when calculating V (interaction between different orbitals). During this month I have been working with atoms whose valence orbitals are S and P, and I understand that for these orbitals, not being very localized like the D orbitals, it is necessary to work with U and V, where V responds to the coulomb interaction between orbitals of neighboring atoms. Thank's for your attention. Best regards.
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