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Pseudopotentials Use for to get specific charge of atom

Posted: Sat May 06, 2023 11:29 am
by SKM
hi
May i know how to get specific valence of atom by using Pseudopotentials?
Say for example i want Zn2+.
I checked POTCARs of 3 types given in PBE all shown same orbitals and electrons. what is the difference in potentials then? or am i checking wrong?

$grep VRH POTCAR_Zn
VRHFIN =Zn: d10 p2

$grep VRH POTCAR_Zn_sv_GW
VRHFIN =Zn: d10 p2

$ grep VRH POTCAR_Zn_GW
VRHFIN =Zn: d10 p2

Re: Pseudopotentials Use for to get specific charge of atom

Posted: Mon May 08, 2023 7:57 am
by merzuk.kaltak
Dear SKM,

The difference of the three POTCARs is the number of electrons considered as valence electrons, respectively frozen electrons.
Zn has the following electronic configuration [Ne] 3s2 3p6 4s2 3d10, which often is abbreviated as [Ar] 4s2 3d10.
For instance the header of POTCAR_Zn

Code: Select all

  PAW_PBE Zn 06Sep2000                   
   12.0000000000000     
...
tells you that this potential describes Zn with 12 valence electrons. The remaining inner electrons, (electronic configuration of [Ar] ) is considered as frozen.

The header of POTCAR_Zn_sv_GW

Code: Select all

  PAW_PBE Zn_sv_GW 05Dec2013                 
   20.0000000000000     
...
shows that this potential puts 20 electrons into valence. That is, electrons 3s2 3p6 4s2 3d10 are valence electrons, while those of [Ne] are considered to be frozen.

It is not possible to change the number of valence electrons of the potential.
However, you can change the number of electrons in the unit cell using NELECT.