[Wien] LDA+U

[stargmoon]

Dear, Stefaan,
 
Thanks a lot.
 
I can't find out Novak's slide and Blaha's paper on CuO2 (I remembered once time I saw this paper) right now. If someone else know this slide and paper, please let me know. I will highly appreciate your kindness.
 
Best

Stefaan Cottenier <Stefaan.Cottenier at fys.kuleuven.ac.be> wrote:

> But I don't understand what you mean by saying "even two LDA+U energies
with the
> same scheme are not necessarily comparible".

If you calculate the total energy at e.g. two different lattice constants,
and you use twice the same LDA+U scheme (either SIC, or AMF, ...), then it
is strictly spoken not guaranteed that the value of the total energy will be
lower for the lattice constant that is closest to equilibrium. At least you
should check whether the density matrices of the relevant atoms are
qualitatively the same in both cases. If they are, you have a good chance
that you are allowed to compare the energies. But absolute certainty will
never be there.

> Another problem is, the orders of the d band split under different LDA+U
scheme, that is,
> SIC and AMF, in my calculations are different. Is it reasonable?

I think so. Different LDA+U schemes have different effects, dependent on
which parts of the bands are already filled by LDA. There is a good slide to
illustrate this from a talk by Pavel Novak (I'm not sure whether it is
available on the web), and probably also in a recent paper on CuO2 by Peter
Blaha this is explained (hope I'm not wrong).

Stefaan

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