[Pw_forum] question on parallelism on bands

[Paolo Giannozzi]

On Mon, 2014-05-26 at 12:00 +0200, pascal boulet wrote:

> I have to run calculations on a rather big system: 35.9x35.9x71.8 bohr, 
> 384 atoms, 1280 bands and few k-points (at most 6). I would like to 
> parallelize the calculations on the bands 

unless you are using hybrid functionals, there isn't a real advantage 
in "band" parallelization for pw.x. 

> but I am not familiar with this. I have up to 50x12=600 procs at disposal. 
> I envisage to use 144 procs and the following options for pw.x:
> -bands 12 -ntg 12 -ndiag 64

> Would you say these are more or less adequate parameters ?

I would say no: too few processors for plane wave parallelization.

Paolo

> Thank you for your help,
> Pascal
> 
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-- 
 Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
 Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
 Phone +39-0432-558216, fax +39-0432-558222