[Wien] LSDA+U for triclinic system

[Pavel Novak]

Dear Hua Wu,

did you perform calculation with or without the spin-orbit coupling? In
systems lacking the inversion center orbital moment may be induced even
without s-o presence. Look whether this happened in your case. LDA+U might
in this case stabilize some funny configuration.

Pavel Novak

On Mon, 25 Oct 2004, Hua Wu wrote:

> 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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> >
> >
> >                                       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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