[Pw_forum] Pseudopotential troubles

[Paolo Giannozzi]

On Oct 4, 2006, at 17:48 , Miguel Martínez Canales wrote:

> Anyway, I have another more profound question. I don't understand  
> why this pseudopotential input is terribly flawed (its result is).
>
>  &input
>      title='Ca',
>      zed=20.0,
>      xmin=-6.0,
>      dx=0.0200,
>      rmax=80,
>      rel=1,
>      beta=0.3,
>      rlderiv=2.7,
>      eminld=-4.0,
>      emaxld=4.0,
>      deld=0.02d0,
>      nld=4,
>      config='[Ar] 3d0 4s2 4p0',
>      iswitch=3,
>      dft='PBE',
>  /

you do not need to specify the radial grid and other optional variables

>  &inputp
>    pseudotype=3,

that is, ultrasoft

>    lloc=-1,
>    rcloc=2.1,

rcloc should be larger than any rc

>    tm =.false.,
>    nlcc =.true.,
>    rho0 =0.01,
>    file_pseudopw='Ca.pbe-van.UPF',
>    file_screen='ld1ps.screen'
>  /
> 3
> 3D  3  2  0.00  0.00  2.40  2.40
> 4S  1  0  2.00  0.00  2.68  2.68
> 4P  2  1  0.00  0.00  2.59  2.59

you asked for a US PP but rc  for norm-conserving and ultrasoft
pseudization are the same. These values for rc seem to me too
large for 3d, too small for 4s and 4p. If you plan to use Ca for
high-pressure studies, you should consider using 3s and 3p
semicore states in valence. Example:

&input
      atom='Ca',
      rel=1,
      config='[Ar] 3d0 4s0 4p0',
      iswitch=3,
      dft='PBE'
/
&inputp
    pseudotype=1,
    lloc=2
    nlcc =.true.,
    file_pseudopw='Ca.pbe-nsp-1.UPF',
    rho0=0.01
/
3
3S  1  0  2.00  0.00  1.20  1.20
3P  2  1  6.00  0.00  1.30  1.30
3D  3  2  0.00  0.00  1.40  1.40

(notice that some versions of the atomic code yield a wrong Zval
in a case like this: it should be checked and changed in the *UPF
file)

> Another question I have is how to add additional projectors per  
> orbital,
> such as the ones used in Paolo Gianozzi's pbe pseudopotential.

???

Paolo