Probabilistic approximations have previously been shown to extend the ability of atomistic simulations to measure diffusivities of spherical diffusant molecules as small as 1.0e-9 sq cm / s. This model has been augmented to include non-spherical molecules by the explicit inclusion of rotational modes. Simulation times of 1/10th microsecond for Carbon Dioxide in PDMS have been achieved with modest usage of computing resources. The techniques presented take advantage of advanced computing environments including MPI, pthreads, and GPGPU resources at the Texas Advanced Computing Center.
