[QE-users] Does d3q work with recover/restart mode?

[Kanka Ghosh]

Thanks Lorenzo! Meaning I can just use the keyword restart=.true. in d3q input for resuming the calculation ?


Regards,
Kanka


Kanka Ghosh
Postdoctoral Researcher
I2M-Bordeaux
University of Bordeaux, CNRS UMR 5295
Site: Ecole Nationale Supérieure des Arts et Métiers
Bordeaux-Talence 33400

----- Original Message -----
From: "Lorenzo Paulatto" <paulatz at gmail.com>
To: "users" <users at lists.quantum-espresso.org>
Sent: Sunday, September 20, 2020 10:55:44 AM
Subject: Re: [QE-users] Does d3q work with recover/restart mode?

> I am using d3q code, embedded in QE for anharmonic phonon scattering 
> calculations with a 44 atom system. My university server has a 
> limitation for runtime to maximum 5 days if I use around 128 processors 
> for the run. the phonon calculations suggest that d3q will take a long 
> time. Therefore, is there any keyword in d3q input which can restart my 
> run after it gets stopped after a certain time? Like recover=.true. options?

Dear Kanka,
this is what I wrote in the d3q manual several years ago:

--
When restart is true, the code will check existing fild3dyn files and 
skip the calculation of any triplet that has already been computed. This 
option can also be used to refine a grid calculation, e.g. if you have 
already computed a 2x2x2 grid and want to compute a 4x4x4 one, simply 
restart with the finer grid and the same input parameters, and the 
triplets from the coarser grid will be skipped automatically.

Restart of partially-computed q-points is currently implemented but 
disabled because 1) it is still unreliable 2) it requires that all 
input/output is safely written to disk, which makes the calculation much
slower. You can activate it modifying the code at your own risk!
--

On top of that, I'll add that I've never had the need to use the partial 
q-point restart. In your case, you probably only need the 
Gamma-Gamma-Gamma calculation, which is just marginally slower than a 
phonon Gamma calculation.

cheers


> 
> Can anybody help to overcome this issue ?
> Thanks in advanced,
> 
> 
> Regards,
> Kanka
> 
> 
> Kanka Ghosh
> Postdoctoral Researcher
> I2M-Bordeaux
> University of Bordeaux, CNRS UMR 5295
> Site: Ecole Nationale Supérieure des Arts et Métiers
> Bordeaux-Talence 33400
> 
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-- 
Lorenzo Paulatto - Paris
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