[Wien] Okay to combine mBJ, spinorbit, and LDA+U?

[Laurence Marks]

If it is a decent insulator I would do LDA+U directly; often it
converges better and since the lattice parameter and forces change you
do not gain much by first doing LDA/GGA. Normally LDA+U is stable,
often more stable that LDA/GGA. Volume optimization should be done
first, then min_lapw or MSR1a. Better is to do MSR1a or min_lapw at
each volume.

Then add -so, mBJ as appropriate with the optimized positions.
However, I not sure if mBJ+U is appropriate (I doubt that it is). It
might be that LDA+U positions are a better approximation for mBJ, not
sure. One way is to minimize the forces with mBJ using MSR1a (not
min_lapw/PORT) and compare them to LDA+U. If they are the same then
you are in good shape, needs testing. Maybe someone has....

N.B., it is completely fine to minimize positions in mBJ using MRS1a
-- do not use min_lapw/PORT, it will not be correct. MSR1a does not
care that the energy is incorrect whereas min_lapw/PORT does.

On Thu, Aug 16, 2012 at 2:44 PM, Jeff Spirko <spirko at lehigh.edu> wrote:
> Is it okay to use spinorbit and LDA+U with mBJ?
>
> I would guess it is done like this:
>  * Check that forces <10 mRy/au with plain LDA or GGA.  Reduce via min_lapw.
>  * Volume optimization (if desired) with plain LDA or GGA to reduce
> absolute pressure.
>  * Set up LDA+U (Sec 4.5.6) and use -orb flag from now on.
>  * Need to converge LDA+U???
>  * Follow mBJ instructions (Sec 4.5.9).
>  * After mBJ+LDA+U is converged, follow spinorbit instructions (Sec 4.5.5).
>  * For spinpolarized, check whether atoms became nonequivalent
> (affects case.inso, case.inorb,
>     case.indmc, case.in1c, basically any input file with atom lists or indices)
>  * touch .fulldiag (necessary because klist can change???)
>  * Do final run with -so -orb
>
> Best regards,
> --
> Jeff Spirko   spirko at lehigh.edu   WD3V   |=>
>
> The study of non-linear physics is like the study of non-elephant biology.
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-- 
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