MOLECULAR-DYNAMICS SIMULATION AND INELASTIC NEUTRON-SCATTERING

The molecular dynamics simulation method is discussed with specific reference to inelastic neutron scattering. A brief description of the two methods is presented and the relationship between them is explored. Inelastic neutron scattering is subdivided into two main areas, incoherent and coherent scattering, and some examples from the literature are reviewed for cases where the neutron inelastic scattering law is calculated. In addition, a detailed simulation of the diffusion of methane in the zeolite ZSM-5 is presented and compared with experiment. The simulation results provide insight into the nature of the intracrystalline diffusion of the adsorbate, while also providing the expected neutron scattering function. A direct comparison of the calculated and measured scattering laws indicates that there is general agreement between experiment and theory although the interpretation of quasielastic scattering using a Langevin diffusion model is inappropriate. The computer simulation model provides an unambiguous link between experiment and the microscopic origin of the observed quasielastic broadening.