[Wien] LDA+U for La2O3

[SIC CAS]

--- Peter Blaha <pblaha at zeus.theochem.tuwien.ac.at>
wrote:

> > Still on the LDA+U for La. It should be true that
> the
> > LDA+U plays less role for the nearly empty 5d
> band.
> > However, why does LDA+U shift up the completely
> empty
> > 4f band as shown in Czyzyk's PRB 49 14211(94)
> paper.
> > The authors used U=11.0 eV for the La 4f band in
> that
> > paper.
> 
> Because empty states are shifted by U/2 upwards.
> 
 
1. That is true in the SIC approach. Is that still
true in the AMF approach where average occupation <n>
( not 1/2) of a band is used. For any empty band, <n>
equals to zero, right?

2. If U/2 is always there, how does that affect the
nearly empty d band for element La?

3. U for occupied bands normall increases a little the
total energy of a system. If U is applied only to the
unoccupied band, such as 4f of La, how does that
affect total energy?

Thanks for answering my questions.

WQ



		
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