[Wien] LDA+U

[Dr. B.R.Sahu]

PRB vol 67, Pg 075102 year 2003.

sahu


On Fri, 20 Feb 2004, stargmoon wrote:

> 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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