Thanks, Tom. This was then my misuderstanding of the explanation of force components, rather being those in the forces.f90 module. Much appreciated, Adam ________________________________ From: users <[email protected]> on behalf of Tom Demeyere via users <[email protected]> Sent: 04 January 2024 1:34 AM To: Quantum ESPRESSO users Forum <[email protected]> Subject: Re: [QE-users] forc conv thr not converging force components?
CAUTION: This email originated from outside the organisation. Do not click links or open attachments unless you recognise the sender and know the content is safe. If my memory serves me correctly “forc_conv_thr" does not correspond to the max forces on any atoms, I don’t remember exactly how it is calculated but it is a more complex expression. By experience it is not always possible to reach very low forces on all atoms, especially if you are using some functional/corrections where the forces are not always perfectly consistent with the energy. If you made sure that conv_thr is small enough so that non-scf correction to the forces is extremely small you might want to call pw.x as an energy/forces evaluator and interface it with a more specialised optimiser. Scipy(L)BFGS often does the trick for me. ----------------------------------------- Tom Demeyere MSc PhD student Skylaris Research Group School of Chemistry, University of Southampton On 28 Dec 2023, at 16:39, Adam Michalchuk <[email protected]> wrote: You don't often get email from [email protected]<mailto:[email protected]>. Learn why this is important<https://aka.ms/LearnAboutSenderIdentification> CAUTION: This e-mail originated outside the University of Southampton. Dear all, I appreciate this topic has been discussed a number of times in the forum, with the answer that all components of all forces should satisfy the forc_conv_thr. This leads me to my probably very simple query that likely stems from a misunderstanding. when I run a vc-relax calculation with e.g. a very tight forc_conv_thr=1.0D-5, my calculation finishes 'successfully' with e.g.: atom 1 type 3 force = 0.00000250 0.00000250 0.00000250 atom 2 type 3 force = 0.00000432 0.00000559 0.00000432 atom 3 type 3 force = 0.00000432 0.00000432 0.00000559 atom 4 type 3 force = 0.00000559 0.00000432 0.00000432 atom 5 type 2 force = -0.00000391 0.00000100 0.00000100 atom 6 type 2 force = 0.00000361 -0.00001336 -0.00001336 atom 7 type 2 force = 0.00000100 -0.00000391 0.00000100 atom 8 type 2 force = 0.00000100 0.00000100 -0.00000391 atom 9 type 2 force = -0.00001336 -0.00001336 0.00000361 atom 10 type 2 force = -0.00001336 0.00000361 -0.00001336 even if I put rather ridiculous thresholds of forc_conv_thr=1.0D-7 it makes no real difference to the force components: atom 1 type 3 force = -0.00000456 -0.00000456 -0.00000456 atom 2 type 3 force = 0.00000832 0.00001867 0.00000832 atom 3 type 3 force = 0.00000832 0.00000832 0.00001867 atom 4 type 3 force = 0.00001867 0.00000832 0.00000832 atom 5 type 2 force = -0.00000414 -0.00000409 -0.00000409 atom 6 type 2 force = -0.00000040 -0.00004042 -0.00004042 If I understand the output correctly, it appears as though some force components have converged fine, though quite a few components have not reached the threshold, and changing the threshold makes little difference. As we do a lot of work on vibrational dynamics in dispersion bound crystals, tight forces are usually quite important. We've recently moved into using QE and I'm trying to get to grips with how to control the forces in QE optimisations but am clearly missing something. Could anybody please point me in the right direction? Many thanks in advance, Adam Adam Michalchuk University of Birmingham UK _______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu<http://www.max-centre.eu/>) users mailing list [email protected]<mailto:[email protected]> https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
