[Pw_forum] VCA (was: no subject)

[Paolo Giannozzi]

On Jan 10, 2012, at 8:22 , Ali Tavana wrote:

> I am looking for the reference paper for the VCA implementation
> in QE (i.e. virtual.x code).

there is no such paper. This is the VCA implementation in QE,
if I remember correctly:
    V^{(vca)} = V_{loc)^{(vca)} + V_{nl}^{(vca)}
where
    V_{loc)^{(vca)} = x V_{loc}^{(1)} + (1-x) V_{loc}^{(2)}
and
    V_{nl)^{(vca)} = \sum_{ij} |\beta^{(1)}_i> x D^{(1)}_{ij} <\beta^ 
{(1)}_j|
                      +  \sum_{ij} |\beta^{(2)}_i> (1-x) D^{(2)}_{ij}  
<\beta^{(2)}_j|
where
  V_{loc}^{(n)}(r) is the local part of PP n ;
  \beta^{{n)}_i(r) are the projectors for PP n ;
  D^{(n))_{ij} are the (bare) components of matrix D for PP n

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