[Pw_forum] Different convergence behavior in non-collinear SO calculation

[H. Lee]

Dear Prof. Paolo Giannozzi:

Thanks for your reply.

But, according to the change of number of pools, I also changed the number
of cores; therefore, plane waves, fft grid, etc. are distributed equally in
both cases. Also, each diagonalization is carried out within the same
number of cores.

At SCF step, most relevant values over k points are merged by use of
mp_sum, mp_max, etc.

At least to me, this difference seems strange.

Regards.

H. Lee

On Thu, Oct 9, 2014 at 10:02 PM, Paolo Giannozzi <paolo.giannozzi at uniud.it>
wrote:

> On Thu, 2014-10-09 at 20:29 +0200, H. Lee wrote:
>
> > Is this just an inevitable numerical noise?
>
> very likely. Some numerical noise is always there, it
> is usually almost invisible, especially at scf convergence.
> In some known cases of special sensitivity to truncation
> and roundoff errors: noncolinear, spin-orbit, DFT+U, it
> is more visible while self-consistency is reached. No
> easy solution is known (to me at least)
>
>
> P.
>
> --
> Paolo Giannozzi, Dept. Chemistry&Physics&Environment,
> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
>
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