[Wien] LSDA+U for triclinic system

[Hua Wu]

Dear Peter Blaha,

  Thanks for your reply.
  Following your suggestions as below, I preformed new calculations 
with both the Oct2004 and Jun2004 versions, and compared with the
previous results obtained with WIEN2k_2002. For the real-mode 
calculations, three versions yielded the same total energies;
and so did for complex-mode calculations. However, the real-
and complex-mode calculations for the same system gave very 
different total energies as I mentioned before (see below).
 
I checked also the scf file, which does not indicate a presence
of some new ordering due to lowered symmetry in the complex calculations.
Moreover, I don't think this large energy difference of about 1 eV per
transition-metal atom (if it might be accepted ??) can be accounted 
for by an orbital ordering if present. Rather there may be something 
wrong in the WIEN2k complex calculations for a triclinic system ? 

Can you pls reconsider the above problem I reported,
and looking forward to your reply. 

Any suggestions from WIEN2K community are welcome.

thanks a lot -- Hua Wu  

On Tue, 19 Oct 2004, Peter Blaha wrote:

> a) You should consider updating to WIEN2k_04. Many bugs have been fixed by now
> and I'm not sure about your version.
> b) What you describe could be explained by an "orbital ordering" phenomen.
> It would require that the "complex" calc has the lower energy ? and when
> you check partial charges of two atoms, which are identical with inversion,
> could have the same spin moments, but different orbitals should be occupied
> for these two sites.
> 
> >   recently i use WIEN2k_02 to perform LSDA+U calculations
> > for a triclinic system, in which transition-metal atoms
> > see a low point-group symmtry-- only identity and inversion.
> > When i calculated various magnetic structures, the inversion
> > symmetry is absent in some cases, so that complex calculations were done.
> > In order to compare total energies, some magnetic strucutes,
> > which can be in principle and have been calculated in a real mode,
> > are intentionally treated with a lower symmetry and then calcualted
> > in a complex mode.
> > 
> > Then the problem emerges: for the same strucure and using the same
> > input (RKmax, k-points, U ...), the well-converged real and complex
> > calculations give very different (being ~1 eV per transition-metal
> > atom)total energies. But the spin moments are almost the same
> > as they should be.
> > 
> > I would appreciate some idea... and thanks in advance -- Hua Wu
> > 
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> > Wien at zeus.theochem.tuwien.ac.at
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> > 
> 
> 
>                                       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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