Molecular dynamics simulation study of various zeolitic imidazolate framework structures.

We report the results of a series of molecular dynamics simulations on a number of zinc zeolitic imidazolate framework (ZIF) structures together with some lattice dynamics calculations on ZIF-4, providing information about the flexibilities of these structures. The simulations have used a force field we developed based on ab initio calculations of clusters of ligands and metal cations. We have shown that there are instabilities of the structures of some ZIF structures at low temperatures and high pressures. A rigidity analysis based on the Rigid Unit Mode model shows considerable degree of network flexibility, including a significant elastic flexibility.