[DFTB-Plus-User] Parallelization - periodic systems - small unit cell

[Ariadni BOZIKI]

Dear all,


I am running MD simulations using DFTB+ for a small unit cell of 16 atoms. Ideally, my goal is to use a parallelized version of DFTB+ in order to decrease as much as possible the computational cost. So far, I installed the code via conda with MPI. In a supercomputer when I use 1 node and 1 processor, my simulations runs fine. However, when I increase the number of processors I get errors like the one below, according to the number of processors I am requesting each time:


WARNING!
-> Insufficient atoms for this number of MPI processors
ERROR!
-> Processor grid (3 x 4) too big (> 1 x 1)


>From the error itself I understand that the small size of the unit cell does not allow for a higher processor grid. However, is there a way to use more processors? I tried to increase the number of groups in the Parallel section so that I get a distribution of processes over K-points, but it did not work either. I should actually mention here that I have a dense K-point grid of 6x6x6. I was wondering for example if a hybrid MPI/OpenMP-parallelization allows for more processors to be used and in turn a reduction of the computational cost.


I would like to thank you in advance.


Sincerely yours,


Ariadni Boziki
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