[Wien] Converged solution with PRATT

[shamik chakrabarti]

Dear Prof. Blaha,

                       I have reached convergence using PRATT smoothly with
a convergence parameter 0.20. Although, I have switched back to MSR1 for
some cases, for some cases I have got error in mixer again after getting
back to MSR1?
 Sir, whether a well converged solution with PRATT ( using convergence
parameter 0.20.) is reliable?

with regards,

On Thu, 20 Jan 2022 at 22:28, Peter Blaha <pblaha at theochem.tuwien.ac.at>
wrote:

> MSR1a also optimizes positions. A possible mixer error is that spheres
> start to overlap during this optimization. Read the error messages in
> detail.
>
> PRATT does NOT change atomic positions, but attempts only to converge the
> electrons. Be aware: PRATT can with a small mixing give the impression of
> convergence (although it is not), or with a larger mixing diverge. Final
> convergence with PRATT is not easy to reach. You should use it only in rare
> cases where MSR1 has problems and only for some time, then coming back to
> MSR1.
>
> Notice the difference between MSR1 and MSR1a !!!
> Am 20.01.2022 um 10:51 schrieb shamik chakrabarti:
>
> Dear Wien2k users & experts,
>
>                               In the case of structural optimization
> (volume or c/a etc) of some structures, I have encountered an error viz.,
> "error in mixer". However, if I switched the scheme MSR1a in case.inm to
> PRATT, it converges smoothly. Now my queries are;
>
> (1) Is it proper to get a converged solution with PRATT i.e. it is not
> leading to a local minimum?
> (2) Should I always need to obtain the converged solution with MSR1a
> instead of PRATT?..
>
> Looking forward to your advice in this regard.
>
> with regards,
>
> --
> Dr. Shamik Chakrabarti
> Research Fellow
> Department of Physics
> Indian Institute of Technology Patna
> Bihta-801103
> Patna
> Bihar, India
>
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> --
> -----------------------------------------------------------------------
> Peter Blaha,  Inst. f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-158801165300
> Email: peter.blaha at tuwien.ac.at
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-- 
Dr. Shamik Chakrabarti
Research Fellow
Department of Physics
Indian Institute of Technology Patna
Bihta-801103
Patna
Bihar, India
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