Molecular dynamics as a tool to study heterogeneity in zeolites – Effect of Na+ cations on diffusion of CO2 and N2 in Na-ZSM-5

Zeolites typically contain extra-framework cations to charge-compensate for trivalent Al atom substitutions in the SiO2 framework. These cations, such as Na+, directly interact with quadrupolar guest molecules, such as CO2 and N2, which move through their micropores, causing energetic heterogeneity. To assess the effects of heterogeneity in Na...

Water diffusion through a membrane protein channel: A first passage time approach

Water diffusion through OmpF, a porin in the outer membrane of Escherichia coli, is studied by molecular dynamics simulation. A first passage time approach allows characterizing the diffusive properties of a well-defined region of this channel. A carbon nanotube, which is considerably more homogeneous, serves as a model to validate the...

Knudsen self- and Fickian diffusion in rough nanoporous media

The effect of pore surface roughness on Knudsen diffusion in nanoporous media is investigated by dynamic Monte Carlo simulations and analytical calculations. A conceptual difference is found between the roughness dependence of the macroscopic, transport diffusivity and the microscopic, self-diffusivity, which is reminiscent of diffusion in...