[Wien] total energies of different spin states with LDA+U

[Stefaan Cottenier]

I don't remember whether I was involved in the discussion you mention,
but anyway:

For some time, I was convinced about the statement that total energies
with LDA+U did not have the same meaning as total energies with LDA,
because the ad hoc insertion of 'U' breaks the variational procedure
that gives the total energy its meaning. However, someone pointed me to
a paper (from H. Eschrig, I don't have the reference at hand) where it
was shown that *for fixed U* there is a normal variational procedure at
work. That would mean that total energies for fixed U can be compared,
regardless how different the spin states are.

If somebody has similar or different opinions on this topic, I am
interested to hear them.

Stefaan


> Dear Wien2k users and developers,
> 
> I remember a discussion in the mailing-list where some users claimed
> that it was
> not possible to compare total energies within LDA+U for the case of
> very
> different spin states (and correspondingly very different density
> matrices), but
> I couldn't find it on the archives. I don't remember the reasoning
> that person
> followed nor who it was. Does anybody have an idea on this?, is that
> reasoning
> right or is it really possible to compare total energies for very
> different spin
> states?. Does anybody know any reference where this is discussed?.
> 
> Thank you for your opinions,
> 
> -- 
> Victor Pardo (PhD Student)
> Electromagnetism - Applied Physics Department
> University Santiago de Compostela
> Facultad de Fisica, Campus Sur s/n, E-15782 Santiago de Compostela
> (Spain)
> Phone: +34 981 563100 Ext:13960     email: vpardo at usc.es
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> 
> 


-- 
Stefaan Cottenier
Instituut voor Kern- en Stralingsfysica
K.U.Leuven
Celestijnenlaan 200 D
B-3001 Leuven (Belgium)

tel: + 32 16 32 71 45
fax: + 32 16 32 79 85
e-mail: stefaan.cottenier at fys.kuleuven.ac.be


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