[Pw_forum] HYBRID XC not allowed in non-scf calculations

[Eduardo Ariel Menendez Proupin]

Hi Layla and everybody,

Let us forget the nscf calculation for the moment, as my scf calculation
was probably not fine.
I have a strongly anisotropic unit cell, and large enough not to dare to
attempt to build a quasi-cubi one, that would have about 360 atoms. For
anysotropic cell,  INPUT_PW instructs to use

                      exxdiv_treatment = 'vcut_ws',
for this to work one must use
                          x_gamma_extrapolation = .false.,   (b.t.w., it is
not mentioned at INPUT_PW.txt )
then I have to set the value
                          ecutvcut = X ,  ! which is 0.7 Ry in the Si
example.
 so, what is the method followed by using vcut_ws ,  and how to set
ecutvcut ? Are low or high values of ecutwfc more or less accurate or more
or less expensive? Is it the method given by Sorouri, Folkes and Hine in
JCP124, 064105 (2006)?

Thanks
-- 


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

On leave from: Departamento de Fisica, Facultad de Ciencias, Universidad de
Chile URL: http://fisica.ciencias.uchile.cl/~emenendez
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