[Pw_forum] electrostatic potential in CP calculation

[Paolo Giannozzi]

On Apr 3, 2012, at 6:15 , jia chen wrote:

> I am trying to calculate the work function based on CP calculation.  
> In order to do that, I need to figure out the electrostatic  
> potential corresponding to cp eigenvalues in real space. I tried PP  
> post possessing, but the result looks consistent with pwscf, but cp  
> eigenvalues present a shift. I also tried to print out variable  
> vpot, but it looks not like electrostatic potential. I hope some  
> one here has experience dealing with this problem, or some one  
> knows the origin of eigenvalue shift between cp and pwscf and how  
> to calculation that.

I am not sure what "potential" exactly is actually contained in the  
potential
file written by CP. I am quite sure instead about the origin and size  
of the
shift between Kohn-Sham eigenvalues printed by CP and by PWscf. In
recent CP versions, look for "Delta V(G=0)" in the output: this is the
difference between the potential at G=0 for CP and for PWscf.  
Explanations
here: http://www.fisica.uniud.it/~giannozz/public/ewald.pdf

  P.
---
Paolo Giannozzi, Dept of Chemistry&Physics&Environment,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222