Are there any options I should optimize in the input file to maximize the parallel efficiency? Like in the VASP, there are two options NCORE and KPAR controlling how to configure parallel running.


1 Answer 1


There are a couple of levels of parallelism:

  1. For big systems the general rule of thumb is that the diagonalization is the bottleneck for the Siesta calculation. Here, only one flag exists for optimizing the parallel efficiency:
Diag.ParallelOverK true

By default, Siesta uses all cores to diagonalize every k-point. However, if the system is "small", but you have many k-points, say $N_k>N_{processors}$, then using Diag.ParallelOverK might improve efficiency significantly.

  1. Another part is the grid, generally this is very well parallelised and there is not much to gain, the defaults are standardly good.

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