[Pw_forum] elf+US not fully implemented?

[Peter Winey]

Thanks a lot for all the help! Now I have a much better understanding on
this issue.

Best,
-Peter

********************************************
Peter Winey, Ph.D., DuPont
peterwiney at gmail.com
********************************************


On 7/22/08, Stefano de Gironcoli <degironc at sissa.it> wrote:
>
> Dear Peter Winey,
>
> I think the problem with the elf + US is that the local kinetic energy in
> the core region is not well defined.
> In the PAW formalism the all-eletron wave functions can be reconstructed
> and from them the kinetic energy density could be calculated hence this is a
> well defined object, but in the US case you only have the augmentation
> charges that are insufficient to define it.
> In practice, I guess, the choice of NOT adding any augmentation kinetic
> energy is made which is somehow unsatisfactory (hence the "not fully
> implemented" cavet)..
> Notice that even for NC pseudopotential the elf is unphisical in the core
> region
> since the core contribution should in principle also be considered, which
> is not.... not to mentin that the pseudowfc in the core are wrong...
> So in conlusion I think that in general one should trust the calculated elf
> in the interstitial region but NOT in the core region (both for US and NC),
> only PAW, or some PAW-like wfc reconstruction (including core contributions)
> could give good results in the regions.
>
> stefan
>
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