[Q-e-developers] Fwd: possible commit in exx.f90

[Paolo Giannozzi]

Marco Govoni proposes the following patch to reduce 
the computational cost of hybrid functionals, by not
computing terms in the exchange that have zero weight.
Does anybody see any problem with it?

Paolo

On Thu, 2014-07-24 at 14:43 +0000, Marco Govoni wrote:
> Caro Paolo, 
> 
> Pensi si possa mettere la seguente linea nel file exx.f90 in modo da ciclare 
> su jbnd ed ikk quando il peso wg e’ zero? 
> Se wg e’ zero, il totalizzatore dell’energia non dovrebbe incrementare. 
> In questo modo quando nbnd contiene stati vuoti, vengono saltati. 
> 
> Marco
> 
> Index: exx.f90
> ===================================================================
> --- exx.f90	(revision 11099)
> +++ exx.f90	(working copy)
> @@ -1797,6 +1797,8 @@
>         JBND_LOOP : &
>         DO jbnd = 1, nbnd     !for each band of psi (the k cycle is outside band)
>            !
> +          IF ( ABS(wg(jbnd,ikk)) < eps_occ) CYCLE
> +          !
>            IF (noncolin) THEN
>                temppsic_nc = ( 0._dp, 0._dp )
>            ELSE
> 
> 
> --

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