Hello, My system is an organic molecular crystal (atoms C, H, N, O). The cutoff is chosen so there is 2 meV/atom error for SCF energy. The k-point grid 3x2x3 (off-centered) yields perfectly converged SCF energy. But to get faster with the vc-relax, I lowered it to 2x1x2 (off-centered), which introduces an error of only -0.1 meV/atom. I don't know if this is the reason why vc-relax density and pressure oscillate without converging.
I'm currently running v-relax with 3x2x3 grid... waiting for the result (10x slower)... Thank you, Xavier ________________________________ From: users <users-boun...@lists.quantum-espresso.org> on behalf of Paolo Giannozzi <p.gianno...@gmail.com> Sent: Monday, January 25, 2021 9:38 AM To: Quantum ESPRESSO users Forum <users@lists.quantum-espresso.org> Subject: Re: [QE-users] vc-relax with PBE0 not converging Maybe the same problem reported here? https://gitlab.com/QEF/q-e/-/issues/204<https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.com%2FQEF%2Fq-e%2F-%2Fissues%2F204&data=04%7C01%7Cxavbdlt%40uic.edu%7C3fdf0cc0f8bd4cd43e8308d8c14769ce%7Ce202cd477a564baa99e3e3b71a7c77dd%7C0%7C0%7C637471859758045446%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=QCUVoTzncfJfau7FM88IUZSHHmCHJf9wUl50miJJ4W4%3D&reserved=0> Paolo On Mon, Jan 25, 2021 at 4:19 PM Bidault, Xavier <xavb...@uic.edu<mailto:xavb...@uic.edu>> wrote: Hello, I have a molecular crystal (1 unit cell = 56 atoms). I use SG15 ONCV 1.2 pseudopotential and Grimme D2 correction. Using vc-relax with PBE, the structure converges, no problem. But with PBE0, density and pressure oscillate without dampening (see figure below - Pressure remains negative, and not close to zero). Is there any particular strategy with PBE0? * vc-relax with PBE and then starting from the result and use PBE0? * relax with PBE0 and then vc-relax? * any simulation parameter to change (ion dynamics and/or cell dynamics - currently BFGS)? * any strategy with PBE0? [cid:1773a31d564cb971f161] Thank you, Xavier _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu<https://nam04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.max-centre.eu%2F&data=04%7C01%7Cxavbdlt%40uic.edu%7C3fdf0cc0f8bd4cd43e8308d8c14769ce%7Ce202cd477a564baa99e3e3b71a7c77dd%7C0%7C0%7C637471859758045446%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=sd3E5%2FhytwHgry%2Bvhoi4xrI%2F2AwuoSy5%2FOnqdAivFhs%3D&reserved=0>) users mailing list users@lists.quantum-espresso.org<mailto:users@lists.quantum-espresso.org> https://lists.quantum-espresso.org/mailman/listinfo/users<https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.quantum-espresso.org%2Fmailman%2Flistinfo%2Fusers&data=04%7C01%7Cxavbdlt%40uic.edu%7C3fdf0cc0f8bd4cd43e8308d8c14769ce%7Ce202cd477a564baa99e3e3b71a7c77dd%7C0%7C0%7C637471859758055404%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=rLgz1kcGcloPgRTtOcAQJcRXdnlFNRtxNyn5cLZt9vE%3D&reserved=0> -- Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche, Univ. Udine, via delle Scienze 206, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222
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