Hi Iurii, Thank you for comments.
What I understood, is that it helps to distinguish at least two cases: 1- If the energy of the final scf is more or less the same with that of vc-relax, but the final pressure is large, then the cure is just to increase ecut. 2- If the energy of the final scf differs significantly, then it was converged to other state. In this case, the cure is to start a separate scf with new cell parameters and atomic positions. Moreover, I feel that using a relatively large mixing_beta may cause oscillation between metastable states and lead to no scf convergence. Bests, Mahmoud From: Iurii TIMROV via users <users@lists.quantum-espresso.org> To: Quantum ESPRESSO users Forum <users@lists.quantum-espresso.org> Date: Thu, 1 Dec 2022 08:05:28 +0000 Subject: Re: [QE-users] Last SCF step of a vc-relax job in DFT+U > What are the advantages of this choice? Without this "trick", for some systems the final SCF calculation might not converge to the same ground state as in the vc-relax run. 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> on behalf of Mahmoud Payami Shabestari <mpay...@aeoi.org.ir> Sent: Wednesday, November 30, 2022 9:19:52 PM To: Quantum ESPRESSO users Forum Subject: Re: [QE-users] Last SCF step of a vc-relax job in DFT+U I found the following statement in release-notes: New in 6.7 version: * In vc-relax with Hubbard corrections, the final SCF calculation is done by reading atomic occupations from file produced during the vc-relax (rather than recomputing them from scratch). What are the advantages of this choice? Does it inform about possible transition among metastable states? Mahmoud From: "Mahmoud Payami Shabestari" <mpay...@aeoi.org.ir> To: "users@lists.quantum-espresso.org" <users@lists.quantum-espresso.org> Date: Wed, 30 Nov 2022 10:49:09 +0330 Subject: [QE-users] Last SCF step of a vc-relax job in DFT+U Dear All, Hi. As far as I know from, in a vc-relax job for a normal system, when the calculated pressure in the last scf (which starts with optimized lattice parameters and atomic positions, while keeping other input values fixed) is much higher than default 0.5kbar value, it implies that one has to increase ecutwfc, ecutrho, ... until this large difference disappears. In a DFT+U run, I encountered such a problem. But when I performed a separate scf but with optimized cell parameters and atomic positions, I get the optimized value for pressure say 0.01 kbar, which is perfect. I am using QE-7.1. Does it mean that in the last scf run of vc-relax the diagonalised ocuupation matrices are used instead of the values specified in the input? Thanks in advance. Best regards, Mahmoud Payami NSTRI, AEOI, Tehran, Iran Email: mpay...@aeoi.org.ir Phone: +98 (0)21 82066504 --------------------------------------------------------
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