[Wien] lcore change from wien2k_02 to wien2k_03

[Peter Blaha]

>       Perhaps this is an old question, but we were unable to locate a
> discussion of it in the archives.
>       We were trying to check our implementation of wien2k_03 wrt runs
> using the wien2k_02 code and found there is a shift in the total energy
> (~0.04 Ry) which we traced to a small difference in the lcore pgms -- in
> particular the insld.f pgm:
>
>   version_02:
>     271       DO 10 I=1,NP+NPXX
>     272       IF(I.GT.NP)DV(I)=DV(NP)
>     273   10  DV(I)= DV(I)/2./DR(I)
>
>   version_03:
>     271       DVR=DV(NP)
>     272       DO 10 I=1,NP+NPXX
>     273       IF(I.GT.NP)DV(I)=DVR
>     274   10  DV(I)= DV(I)/2./DR(I)
>
>   What this means is that DV(I) was generally discontinuous at RMT in
> version_02 but not in version_03.  This effected only some of the atoms in
> our unit cell; those which have a small tail beyond RMT.   Our questions
> are:
>
> 1.  Should we assume that the version_03 code gives a better
> approximation?

Yes of course.

> 2.  It would be reassuring if one could argue that the energy shift from
> version_02 to version_03 is reasonably constant wrt the valence properties
> of the system.  For example, hopefully it would not effect the valence DOS
> or the lattice relaxation??  Does anyone have experience with this?

I would expect such more or less constant E shift.

However, if there is a large shift, I would be concerned about "charge leakage"
which might affect a lattice relaxation (probably not the DOS, which is quite
insensitive). Ideally, core states have "zero"! wavefunctions outside RMT and
thus the bug of the old version should not make any difference.

How large is the difference in :NEC01 of case.scf ?
Could you include more states as valence ? Could one change RMT ?

Regards
                                      P.Blaha
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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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