Quantum Espresso: Specific Compute Parameters¶
The compute parameters which are specific to Quantum ESPRESSO consist in the Advanced Options, which can be set from within the relevant user interface.
These specific parameters allow for the parallelization of Quantum ESPRESSO computations, as explained in what follows. Detailed explanations on how to best set the values of such parallelization parameters can be found under Ref. 1.
Parallelization of Computations¶
Processors can in general be divided into different "images", each corresponding to a different self-consistent or linear-response calculation which are coupled together.
k-point pools¶
Each image can be subpartitioned into "pools", each taking care of a group of k-points.
band pools¶
Each pool is subpartitioned into "band groups", each taking care of a group of Kohn-Sham orbitals (also called bands, or wavefunctions).
FFT task groups¶
In order to allow good parallelization of the 3D FFT, when the number of processors exceeds the number of FFT planes, FFTs on Kohn-Sham states are redistributed to "task" groups so that each group can process several wavefunctions at the same time.