Gas diffusion in glasses via a probabilistic molecular dynamics

A probabilistic protocol which makes possible the calculation of the diffusivity of light gases in amorphous materials from limited Monte Carlo and molecular dynamics data is presented. Diffusion coefficients are calculated for helium and methane in polystyrene, and for helium, neon, and methane in three pairs of polysulfone isomers. Results include diffusion coefficients as small as 10 − 9 cm 2 ∕ s and are in good agreement with results obtained from traditional molecular dynamics and with available experimental data.