[Pw_forum] HOMO,LUMO isosurface, USPP or NCPP?

[Eduardo Ariel Menendez Proupin]

 Dear Yavar

USPP and NCPP are mathematical methods to approximate the solution of the
same physical problem. Hence, there must be no physically different
results, unless one of the pseudopotentials is faulty. Both types of
pseudopotentials have cutoff radii, which are larger for NCPP than for
USPP. The wavefunctions computed with any pseudopotential should be equal
to the all-electron wavefunctions in the spatial region outside the spheres
centered at each atom with spheres radii equal to the cutoff radii of the
corresponding pseudopotential. Inside any sphere, the wavefunctions are
different and are meaningless. To have the correct wavefunctions inside the
spheres you have any of the following options a) all-electron calculations
(with a different code,e.g. ADF, Gaussian, LMTO, etc), b) use a PP with a
smaller cutoff radius (and larger ecutrho and ecutwfc), c) use PAW
(projector augmented wave).

sincerely yours


Eduardo Menendez Proupin
Departamento de Química Fisica Aplicada
Facultad de Ciencias
Universidad Autónoma de Madrid
28049 Madrid, Spain
Phone: +34 91 497 6706



 Dear QE users.
>
>
> I want to plot HOMO, LUMO isosurfaces. what is the physical origin
> of difference between results from choosing USPP with NCPP?
>  Thanks in advance.
>
>
> -------------------------------------------
> Yavar Taghipour Azar
> PhD Student
> Physics Group, AEOI
> Tehran-Iran
>
> Email: ytaghipour at aeoi.org.ir
> Phone: +98 (0) 21 82064556
> -----------------------------------------------------------
>
>
>
>
>
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