[QE-users] 回复: SCF calculation with SOC fails to converge

[Wang, Aolei]

Dear Paolo,
Thank you for your detailed and insightful reply. It is an honor to receive guidance from you.
There was a typo in my previous email. My original command (which failed) did include the -nt flag for task-group parallelization: mpirun -np 400 pw.x -nk 10 -nb 1 -nt 4 -nd 36.
Best regards,
Aolei Wang
Department of Physics & Astronomy
California State University, Northridge
-----邮件原件-----
发件人: users <users-bounces at lists.quantum-espresso.org> 代表 Paolo Giannozzi
发送时间: 2025年12月4日 6:16
收件人: Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>
主题: Re: [QE-users] SCF calculation with SOC fails to converge

Multiple answers here:

> I could see etot_conv_thr = 1e-7 , this is too strict criteria for 
> total energy convergence

no it's not: 1.0e-7 is fine for most cases

 >  you can try [...] changing diagonalization to cg

this might work in case of errors in diagonalization, but does not solve non-convergence problems. My advice is not to use cg, except very special cases.

 > My original command was: mpirun -np 400 pw.x -nk 10 -nb 1 -nd 36.

400 MPI processes seems to me a large number for a 12-atom cell.

Also: with norm-conserving pseudopotentials, do not set "ecutrho", the default value (4*ecutwfc) is perfectly fine.

 > After removing the -nt flag

there is no -nt flag in the "original command"

 > While the issue is resolved, I am still curious about the root cause.

if the problem arises from the -nt flag, it might be a bug in the "task-group" parallelization, a technique that is still present in the code but that should be replaced by something better (it is useful only with more than hundreds MPI processes, it is hard to maintain and not well suited for GPU porting)

Paolo
--
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche, Univ. Udine, via delle Scienze 208, 33100 Udine Italy, +39-0432-558216

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