[Wien] lapwdm (bis)

[Peter Blaha]

> I did some more tests on the lapwdm 'problem' (?) I posted a few days ago
> (see copy below). I could reproduce the problem in bulk bcc Fe, which makes
> testing much easier. First I converge the case with spin-orbit and with the
> moment in case.inso either along 001 or 100 (010 doesn't seem to work, but
> all these 3 cases should be equivalent anyway). Then I run 'x
> lapwdm -c -so -up' twice: once with '0 0' in case.indmc, once with '1 3'. In
> both cases I see the following output in case.scfdmup:
>
> For '0 0':
> :ORB001:  ORBITAL MOMENT:  0.04682  0.00000  0.00000 PROJECTION ON M
> 0.04682
>
> For '1 3':
> :XOP001  2    -0.02690     0.00000     0.07372     0.04682
>
> This is entirely as I expect: both procedures yield the same orbital moment.
>
> But then, instead of 001 or 100, I specify 110 in case.inso (which gives 8
> instead of 16 symmetry operations). Now both procedures yield *different*
> orbital moments, just as I reported a few days ago for a more complicated
> cell:
>
> For '0 0':
> :ORB001:  ORBITAL MOMENT:  0.03325  0.03325  0.00000 PROJECTION ON M
> 0.04702
>
> For '1 3':
> :XOP001  2     0.00000     0.00000     0.00000     0.00000
>
> I can now repeat my original question on firmer grounds: "Should both
> procedures (00 and 13) be equivalent as I assumed up to now, or do they
> calculate different quantities ?"



It seems the answer is: they can be different when you have a non-unity
local rotation matrix.

0 0 gives the orbital moment in global coordinates
    (i.e. along the direction specified in case.inso)

1 3 uses in addition the local rotation matrix


Check the code in: SRC_lapwdm/output.f

! for <|X|> calculation replace usym by usym*coup
      if(krad.ne.0)then
...
            uhelp(i,j,ii)=uhelp(i,j,ii)+usym(i,k,ii)*coup(ll,mk,mj,2,2)
...

      if(krad.ne.0)then
	write(6,*)'DENSITY MATRIX IN LOCAL COORD. SYSTEM of repre. atom'
        write(6,*)'spin coordinate system according to case.inso'
      endif


PS: I'm not sure what the purpose of this is. Maybe Jan or Pavel can comment
and clarify this.


                                      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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