[Pw_forum] computation time of addusdens subroutine

[Junfeng Qiao]

Dear stefano,

tqr = .true. works really good, according to my rough estimations, it speeds 
up about 5 fold, which makes my calculation feasible.

Thank you so much for your suggestion, it really helps me a lot.

I will delve into the code later to find out other ways to make my calculation 
more efficient.

Thanks for everyone.

Sincerely,
Junfeng Qiao


On Tuesday, July 11, 2017 04:10:05 PM stefano de gironcoli wrote:
> You can try to see if the postprocess code accepts the calculation of
> augmentation charge in real space (tqr=.true. in some namelist , I guess
> electrons)
> If it works it should be faster
> stefano
> 
> On 11/07/2017 16:04, Junfeng Qiao wrote:
> > Dear QE users,
> > 
> > I am currently trying to extract wavefunction |psi|^2 of some bands and
> > kpoints, which can be achieved with plot_num = 7 of pp.x.
> > 
> > However, if I extract large amount of wavefunctions, for example,
> > assigning
> > kpoint(1) = 1, kpoint(2) = 20*20, kband(1) = 1, kband(2) = 300,
> > the pp.x will run for an unbearable long time.
> > 
> > On my cluster (10 intel cpus, total 60 cores), each wavefunction will take
> > about 8 seconds, and do a simple prediction, in total 8 * (20*20) * 300 /
> > 3600 / 24 = 11 days ! It is much more longer than the scf calculations.
> > 
> > After playing with the code(QE v6.1), I found in local_dos.f90 line 392,
> > the call to addusdens() takes up almost all the computation time, other
> > parts are negligible.
> > 
> > While, in this situation, I totally have no ideas how to get out of this
> > trouble, so I am seeking for help in this community: is it possible to
> > speed up this addusdens() part?
> > 
> > Thanks for your time of reading this email, any suggestions will be truly
> > appreciated.
> > 
> > Sincerely,
> > Junfeng Qiao
> > Beihang University (BUAA)
> > Beijing, China
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> > Pw_forum at pwscf.org
> > http://pwscf.org/mailman/listinfo/pw_forum
> 
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