[Pw_forum] nqx=1 in input but full grid in output

[Lorenzo Paulatto]

On 10/21/2014 04:49 PM, Roberto Gaspari wrote:
>
> EXX: grid of k+q point setup nkqs =         42
>
> that is the grid for the Fock operator is as dense as the regular 
> Monkhorst-Pack grid.
>
> Does all this correspond to an expected behavior of pwscf?

Yes it does. Well, I think it does, you do not say how many irreducible 
k-point you have in your system.

nqX=1 means that wfcs at each kpoint only exchange with wfcs at the same 
kpoint. What you ar thinking is having wfcs at any k-point only exchange 
with wfcs at the Gamma point.

A big limiting factor with EXX calculations is that CPU time scales with 
the square of the number of k-points. By setting nqX to a fixed value 
the scaling becomes linear again when nk is bigger than nq.


-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
+33 (0)1 44 275 084 / skype: paulatz
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