Diffusion of acetylene inside Na-Y zeolite: molecular dynamics simulation studies

Dynamics of acetylene molecules adsorbed in Na-Y zeolite cages is investigated using molecular dynamics simulation. The translational motion of the acetylene molecules is shown to involve three different time scales. "Free particle" type diffusion is observed in short time and small length scale. At long time and large length scale, center of mass motion of acetylene is determined by the zeolitic pore topology. Rotational motion of the acetylene is found to be very fast. Detailed analysis of the intermediate scattering function corresponding to the rotational motion showed large-angle jumps that could be described by an m-diffusion model.