[Wien] Finally the report about optimizing the structure with MSR1a and mBJ

[Laurence Marks]

The convergence criteria are about 100 times too small to be
realistic. Use -ec 0.0001 at most, and -fc has no bearing for MSR1a; I
suggest adding -cc 0.00025. With what you have used you are limited by
the noise of the iterative method. If you look in the documentation,
you will see that -vec2pratt is recommended (by me) as it is better
with MSR1a.

When you say "some atoms were fixed" what do you mean? For a
non-centro symmetric structure it is OK to fix one atom, but if you
fix more then your results may well be unphysical.

What matters is not whether MSR1a works with mBJ (it does), rather
whether the atom positions are better in some sense.

On Tue, Sep 11, 2012 at 8:36 AM, Luis Carlos Ogando Dacal
<ogando at ieav.cta.br> wrote:
> Dear Prof. Blaha, Marks and WIEN2k community,
>
>    I finally tried the structure optimization using MSR1a and mBJ
> (without SOC).
>    As I have a previous successful optimization of the structure using
> MSEC1 and PBE (min_lapw), I repeated the same parameters whenever
> possible.
>    The result is that after 200 iterations I did not get the
> convergence with remarkable abrupt changes in ETEST during the
> calculation.
>    Please, let me show the steps I followed for the optimization and
> take a look to see if there is any obvious mistake in the procedure:
>
> 1) init_lapw (using the same parameter as in the previous
> min_lapw-MSEC1-PBE optimization)
>
> 2) create case.inm_vresp (from template)
>
> 3) change NR2V to R2V in case.in0
>
> 4) a short SCF cycle to create case.r2v
>
> 5) change indxc to 28 in case.in0
>
> 6) change indxc again to 50 and save the file as case.in0_grr
>
> 7) a short SCF cycle (6 iterations ) with MSR1
>
> 8) remove case.in0_grr
>
> 9) change to MSR1a in case.inm
>
> 10) finally  run_lapw -ec 0.000001 -fc 0.01 -in1orig -i 200 -it
>
>    Probably you will say that the convergence parameters are too
> strict, but I found them in a paper where a similar calculation where
> performed (using pseudopotentials, not lapw).
>    If you want, I can send you the files generated during the optimization.
>    All the best,
>                   Luis
> PS: some atoms where fixed through case.inM
>
>
>
>
>

-- 
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
www.numis.northwestern.edu 1-847-491-3996
"Research is to see what everybody else has seen, and to think what
nobody else has thought"
Albert Szent-Gyorgi