Ensemble Monte Carlo and full-wave electrodynamic models implemented self-consistently on a parallel processor using perfectly matched layer boundary conditions

We have been using a self-consistent formulation of full-wave electromagnetic solvers and ensemble Monte Carlo techniques to model ultrafast photoconductivity. Our simulations are running on a MasPar machine. This paper will address aspects of this simulation which may interest workers who are simulating not only photoconductive systems but other systems as well which involve electrodynamics, waves and wave phenomena and ensemble Monte Carlo transport models. In particular, we will report on the inclusion of perfectly matched layer approaches to absorbing boundary conditions for electromagnetic waves. These have in the past several years become widely used in computational electromagnetics codes because they reduce error due to spurious numerical wave reflection off of an absorbing boundary by several orders of magnitude. We will also address the issue of computational cost and show that a full-wave electromagnetic approach is more competitive with a Poisson's equation approach than one might believe. Lastly, our system has the feature that the active portion where the electrons and holes lie is in fact a small fraction of the total experimental system's volume. Unless care is exerted one either has a very significant load imbalance problem or high communications overhead. We compare two different tradeoffs between load imbalance and communications overhead.