[Wien] Mini NEWT and/or PORT - what precision can one expect?

[Torsten Andersen]

Dear Lawrence, Stefaan, and Peter,

thank you for your suggestions. Some of them (like the increased -fc 
constraints) I have already tried, without luck. But it seems that my 
-cc 0.0001 might have been a bit too optimistic. I will try the 
suggestions of Lawrence now...

BTW, I am of course using what in other metal calculations have proven 
to be plenty of k-points (441-10000), and large values of rmt*kmax [9-10 
(11 is unstable)].

Best regards,
Torsten Andersen.

Peter Blaha wrote:
>>>I thought this would be straight-forward by changing to "NEWT 0.1" or
>>>"PORT 0.1" in case.inM. However, in NEWT I end up with the
>>>"stp.le.tolx", although there is plenty of space between the MT's, and
>>>in PORT I run into the "curvature condition failed".
>>
>>Probably too obvious, but did you check whether your forces are absolutely
>>converged within 0.1 mRy/au? (wrt basis set and k-mesh) Otherwise you get
>>'random' values (at that accuracy level), and any minimizer will find no
>>conclusion which can possibly lead to error messages somehow.
> 
> 
> And even more important: Did you convege the scf cycle to such high
> precisions (in fact, even to higher precision!) ?
> run_lapw -fc 1   means that forces may have errors in that range. E.g. when
> calculating phonons I need forces converged to 0.05 to 0.01 mRy/bohr.
> Of course this takes some more iterations, but without that you cannot
> relax positions to such a precision.
> 
>                                       P.Blaha
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
> Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
> --------------------------------------------------------------------------
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-- 
Dr. Torsten Andersen        TA-web: http://deep.at/myspace/
AG Hübner, Department of Physics, Kaiserslautern University
http://cmt.physik.uni-kl.de    http://www.physik.uni-kl.de/