[Pw_forum] Zero of the electrostatic potential ?

[Paolo Giannozzi]

On Jun 23, 2009, at 11:29 , Vladan Stevanovic wrote:

> where the code places the vacuum level in such calculations
> (nonperiodic systems in a big cell) ? To formulate differently,
> is it possible to compare directly KS eigenvalues from different
> calculations ?

short answer: no.

V(G=0) is calculated (finite or infinite systems doesn't matter)
as described in the attached notes. CP and PWscf have a
different definition of V(0) so you get the same eigenvalues,
but displaced

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