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| For many complex problems, a single core is not enough to finish the calculation in a reasonable time.
| | #REDIRECT [[:Category:Parallelization]] |
| VASP makes use of parallel machines splitting the calculation into many tasks.
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| By default, VASP distributes the number of bands ({{TAG|NBANDS}}) over the available cores.
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| But it is often beneficial to add parallelization over the FFTs ({{TAG|NCORE}}), the '''k''' points ({{TAG|KPAR}}), and separate calculations ({{TAG|IMAGES}}).
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| All these tags default to 1 and divide the number of cores among the parallelization options.
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| There may also be additional parallelization options for some algorithms in VASP.
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| ::<math> | |
| \text{total cores} = \text{cores parallelizing bands} \times \text{NCORE} \times \text{KPAR} \times \text{IMAGES} \times \text{other algorithm-dependent tags}
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| </math>
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| VASP makes use of [[Hybrid_MPI/OpenMP_parallelization|OpenMP]] and [[OpenACC_GPU_port_of_VASP|OpenACC]] when possible.
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| Note that these options conflict with the {{TAG|NCORE}} parallelization.
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| ==Optimizing the parallelization==
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