[QE-users] Regarding the optimization of SCF calculations in supercells

[Lorenzo Paulatto]

Hello Mateus,

you can compute these force constants with a much smaller cost using my 
code "d3q" that uses perturbation theory in reciprocal space. The entire 
calculation for the 4×4×4 grid with a 12×12×12 shifted grid of k-points 
only takes around 12 hours on 64 CPUs.

(I can provide inputs and outputs on request, as it is all published 
results)

cheers



On 22/05/2025 20:03, Mateus Corradini Lopes wrote:
> Dear all,
>
> I have recently been working on obtaining transport properties for 
> certain types of materials. One of the parts of the work is to obtain 
> the lattice thermal conductivity (\kappa_latt), so I'm trying to use 
> phono3py+Quantum Espresso to calculate the supercell and obtain the 
> force constants.
>
> At the moment I'm trying to calculate the \kappa_latt of GaAs as a 
> test, I've already managed to generate the supercells (4x4x4 and 3x3x3 
> based on the conventional GaAs cell, which gives 512 and 216 atoms 
> respectively) and I've used phono3py's --cutoff-pair to reduce the 
> number of inputs, but even though I've tried various ways of running 
> the calculation I haven't found a way to make it feasible in terms of 
> computational time and RAM (the lowest I could get was “Estimated 
> total dynamical RAM > 115.43 GB”). I have access to a cluster with 480 
> processors (10 nodes with 48 processors each) and I would like to know 
> what is the best way to run this system, in terms of optimizing the 
> input and the parallelism used, balancing precision and computational 
> time.
>
> Ps. I'm attaching an example of the input I'm currently using.
>
> Thank you in advance,
>
> M.Sc. Mateus Corradini Lopes
> PhD. student
> Gleb Wataghin Institute of Physics - Unicamp
>
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-- 
Dr. Lorenzo Paulatto
IR IMPMC - CNRS UMR 7590 / Sorbonne Université / MNHN
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