Dear Yang Gang, I am learning QE but I would proceed like this: https://docs.google.com/document/d/1rA9VMpg_cQrmGpTiAalpF6J4LEIzDU2MrbSXNosxNI0/edit?usp=sharing I hope it helps.
Best regards, Em qui., 27 de jan. de 2022 às 09:23, Gang Yang <gang.y...@ec-lyon.fr> escreveu: > Dear QE experts: > I am doing phonon dynamics calculation. I want to obtain the second force > constants using QE ph.x and q2r.x module. For the ph.x calculation, how to > choose properly the parameters value of nq1,nq2 nq3 in the ph.x inputfiles. > As you know, the parameters nq1,nq2,nq3 determine the number of outputfile > dyn. I saw someone using nq1=2,nq2=2, nq3=2. or nq1=8,nq2=8,nq3=8. et al . > if the paramter nq1,nq2 nq3 is too large, the calculation time is too long. > if the parermeters nq1,nq2, nq3 is too small, I don't konw whether it will > affect the precision of second force constants. in addtion, i also found > the some specical nq1,nq2,nq3 value are not allowed for asymmetric > structure. therefore, my question is if I want to obtain a reasonable > second force constants using q2r.x, how I can choose the parameters value > of nq1,nq2 nq3 when I using ph.x calculation in 10 atom primitive cell? > Thank you very much. > have a good day. > > Yang Gang > Institut des Nanotechnologies de Lyon (INL) - UMR5270 > Ecole Centrale de Lyon > 36, Avenue Guy de Collongue > 69 134 Ecully Cedex > Tél.: +33 (0)7 64 83 01 70 > > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu) > users mailing list users@lists.quantum-espresso.org > https://lists.quantum-espresso.org/mailman/listinfo/users -- Marcelo Falcão de Oliveira Professor Associado Departamento de Engenharia de Materiais EESC - USP Av. João Dagnone, 1100, Jd. Sta Angelina CEP: 13563-120, São Carlos - SP - Brasil e-mail: marcelo.fal...@usp.br Fone: (16) 3373-9583 Fax: (16) 3373-9590 Agenda: http://www.google.com/calendar/embed?src=marcelo.falcao%40usp.br&ctz=America/Sao_Paulo&mode=week
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