  Scanning transmission electron microscopy (STEM) is an extremely versatile
method for studying materials on the atomic scale. Many STEM experiments are
supported or validated with electron scattering simulations. However, using the
conventional multislice algorithm to perform these simulations can require
extremely large calculation times, particularly for experiments with millions
of probe positions as each probe position must be simulated independently.
Recently, the PRISM algorithm was developed to reduce calculation times for
large STEM simulations. Here, we introduce a new method for STEM simulation:
partitioning of the STEM probe into "beamlets," given by a natural neighbor
interpolation of the parent beams. This idea is compatible with PRISM
simulations and can lead to even larger improvements in simulation time, as
well requiring significantly less computer RAM. We have performed various
simulations to demonstrate the advantages and disadvantages of partitioned
PRISM STEM simulations. We find that this new algorithm is particularly useful
for 4D-STEM simulations of large fields of view. We also provide a reference
implementation of the multislice, PRISM and partitioned PRISM algorithms.
