Dear Lorenzo, 

Yes it took little more than 5 days to compute only the first q-point. anyway 
it seems that I should use 1x1x1 grid instead of 2x2x2. But are you suggesting 
to do the single mode calculation with 1x1x1 grid or the "mode=full" using the 
1x1x1 grid? 

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 


From: "Lorenzo Paulatto" <[email protected]> 
To: "users" <[email protected]> 
Sent: Friday, December 4, 2020 9:09:50 AM 
Subject: Re: [QE-users] D3Q code stopped due to davcio error 




Thanks for pointing out the storage issue. Yes, I am running it at the French 
computing centre (University of Bordeaux's cluster system (curta, mcia)). Here 
I am attaching the d3q output file. Indeed, it was in the process of computing 
the second q-point triplet. 




I do not have access to Bordeaux cluster, but I could ask it if you need that I 
look at the code. That said, I see that to compute the first q-point it took 
about 5 days, it will take at least a month to do the second point ! Because it 
has less symmetry the code needs to compute 2x more k-points and 3x more 
perturbations. 

BQ_BEGIN




"Maybe for such a large system you can get some decent force-constants already 
from (0,0,0) alone" 





In that case, you mean to implement the "mode=gamma-only" tag? 

BQ_END


Not really, the triple (0,0,0) is in itself the 1x1x1 grid, and you can threat 
it as such. Thanks to some Fourier interpolation trickery, you can use it to 
get the D3 matrices at any point. Also, the d3_qq2rr code is not particularly 
optimized, and is not parallelized I'm not sure you would manage to compute the 
Fourier transform of the 2x2x2 grid anyway. 

You have to keep in mind that the 3-body force constant become huge very 
quickly with the number of atoms and the size of the grid: each D3 matrix has 
(3*nat)^3 complex elements, and a grid n x n x n contains n^6 power triplets 

In your case, the 2x2x2 grid would use about 2.2GB of RAM, which is probably 
still feasible, but i would try the 1x1x1 first. 




cheers 

BQ_BEGIN









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 


From: "Lorenzo Paulatto" [ mailto:[email protected] | <[email protected]> ] ​_ 
To: "users" [ mailto:[email protected] | 
<[email protected]> ] 
Sent: Thursday, December 3, 2020 11:23:58 PM 
Subject: Re: [QE-users] D3Q code stopped due to davcio error 

task # 71 
BQ_BEGIN

from davcio : error # 5011 
error while writing from file 
".//D3_Q1.0_0_0_Q2.0_0_-1o2_Q3.0_0_1o2/scf.d1.dq1pq1.72" 


BQ_END





I guess it may have run out of space, d3q uses a ton of disk space and there is 
not easy way to avoid this. If you are running on any of the French computing 
centers I can try to have a look directly. 

I do not think the change in number of CPUs could cause this problem, but if 
you provide the full output I can check. Also, 44 atoms is a lot for the d3q 
code, it seems like you're running the second q-point triplet, which is of kind 
(0,q,-q), it takes much more time and disk space than the triplet (0,0,0). 
Maybe for such a large system you can get some decent force-constants already 
from (0,0,0) alone 
cheers 


BQ_BEGIN


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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BQ_END

_______________________________________________ 
Quantum ESPRESSO is supported by MaX ( [ http://www.max-centre.eu/ | 
www.max-centre.eu ] ) 
users mailing list [ mailto:[email protected] | 
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_______________________________________________
Quantum ESPRESSO is supported by MaX ( [ http://www.max-centre.eu/ | 
www.max-centre.eu ] )
users mailing list [ mailto:[email protected] | 
[email protected] ] [ 
https://lists.quantum-espresso.org/mailman/listinfo/users | 
https://lists.quantum-espresso.org/mailman/listinfo/users ] 

BQ_END

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users mailing list [email protected] 
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