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Hi all,

I have been testing the performance of VASP on the cluster in my institute and have noticed a very poor speed up with the number of nodes for the particular problem I am tackling.

Basically from 1 to 4 cores I see a nice improvement, but beyond that the computing time might even increase with the number of nodes, I guess because of communication issues.

I would like to know what is the limiting factor in my case. I have a two atom unit cell and am doing a HSE06 type calculation with a varying number of kpoints, ranging from 4x4x4 to 10x10x10.

Is the speed-up bad because of the very low number of atoms? Is it an intrinsic issue related to HF-type calculations?

Thanks

<span class='smallblacktext'>[ Edited ]</span>

Have you tried massive parallelization?
http://cms.mpi.univie.ac.at/vasp/vasp/P ... .html#4641

VASP won't allow me to set NPAR to anything different than the number of cores for HF calculations, so this is not an option. Changing LPLANE only makes things worse...