[Pw_forum] Disparities between HPC's

[Lorenzo Paulatto]

On 7 February 2013 16:58, Kucukbenli Emine <emine.kucukbenli at epfl.ch> wrote:

>  3.encourage users to report these pseudopotentials because i think it is
> most of the time due to a very hard pseudo..
>
>
...or a very soft pseudo. If the augmentation spheres of different pseudos
overlap, the generalized orthogonality of projectors and atomic
pseudo-wavefunctions does not hold anymore: for functions from different
atoms it is assumed but not imposed. Under this condition the positive
definiteness of dr2 is not guaranteed any more.

Another face of this problem: when using real-space augmentation charge you
will get wrong total charge. The error message tells you to "increase
cutoff", but it will not not help in this case.

It's a tricky situation: if the pseudo is too hard \beta delocalizes
because of aliasing in the Fourier transform; if the pseudo is too soft
\beta just overlaps. In any case the result is that we have interference
between different augmentation spheres.

I've spent an afternoon in a naive effort to reimpose orthonormality on the
G-space grid but could not finish before having to move on more urgent
matters. If any good-soul has some time to dedicate to this issue...

-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
phone: +33 (0)1 44275 084 / skype: paulatz
www:   http://www-int.impmc.upmc.fr/~paulatto/
mail:  23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05
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