[Pw_forum] about generating pseudopotential

[Malgorzata Wierzbowska]

On Thu, 12 Oct 2006, Amin Babazadeh wrote:

> dear users
>
> When we use GGA approximation we can use many exchange-correlation potential
> for example PW91 exch-corr GGA ,PBE (Perdew-Burke-Ernzerhof), EV-GGA
> (Engel-Vosko),.......
> I found some of the pseudopotential in the
> http://www.pwscf.org/pseudo.htmthat have been generated with some of
> the exch-corr
> functions but i need the pseudopotential with EV-GGA (Engel-Vosko) exch-corr
> potential. I want to generate this potential but i don't know if i can do it
> whit using  USPP ``*U*ltra*S*oft *P*seudo*P*otential'' code or not. I
> haven't worked whit this code until yet and i want to know that if this code
> in capable of doing my job i start learning it.
>
> Exactly what i need is
> I want to use the function that Engel and Vosko proposed for
> exchange-correlation potential {Exact exchange-only  potential  and  ....,
> Phys.Rev  B47 13164 (1993)} instead of  PW91.
>

  The ultrasoft code uspp-735 can only generate USPP with
the DFT functionals:
exfact: specify the type of exchange-correlation
         (CA means ceperley-alder in perdew-zunger parametrization)
            0  LDA: CA
           -1  LDA: wigner
           -2  LDA: hedin-lundquist
           -3  LDA: gunnarson-lundquist
            1  GGA: CA + Becke88 + LYP
            2  GGA: CA + Becke88
            3  GGA: CA + Becke88 + Perdew86
            4  GGA: PW(91)
            5  GGA: PBE(96)

To change the functional you need to set the proper exfact parameter
in the input_ae. For the exact exchange you need other tools.
See EXX_example in the last espresso version and ask Stefano de Gironcoli
for more details.

   Gosia

> I will appreciate if some one help me and tell me if it is possible to
> change exchange correlation potential in USPP or recommend me a code for
> generating pseudopotential.
> Sincerely yours
>