Distributed-memory parallelization of the Wigner Monte Carlo method using spatial domain decomposition

The Wigner Monte Carlo method, based on the generation and annihilation of particles, has emerged as a promising approach to treat transient problems of quantum electron transport in nanostructures. Tackling these simulations in multiple spatial dimensions demands a parallelized approach to facilitate a practical application of the method in order to investigate realistic problems, due to the otherwise exorbitant execution-times and memory requirements. Because of the annihilation step, a straight-forward parallelization of the Wigner Monte Carlo code is not possible, since sub-ensembles of particles can not be treated independently. Moreover, the large memory requirements of the annihilation procedure presents challenges when working in a distributed-memory setting. A solution to this problem is presented here with a parallelization approach using a spatial domain decomposition, implemented using the message passing interface. The presented benchmark results, based on standard one-dimensional examples, exhibit a good efficiency in the scalability of not only speed, but also memory consumption, which is paramount for the simulation of realistic devices.