Molecular dynamics simulations on gate opening in ZIF-8: Identification of factors for ethane and propane separation

Gate opening of zeolitic imidazolate frameworks (ZIFs) is an important microscopic phenomenon in explaining the adsorption, diffusion, and separation processes for large guest molecules. We present a force field, with input from density functional theory (DFT) calculations, for the molecular dynamics simulation on the gate opening in ZIF-8. The computed self-diffusivities for sorbed C1 to C3 hydrocarbons were in good agreement with the experimental values. The observed sharp diffusion separation from C₂H₆ to C₃H₈ was elucidated by investigating the conformations of the guest molecules integrated with the flexibility of the host framework.