Structures and dynamics of CO<inf>2</inf> molecules in zeolitic imidazolate frameworks-8: Molecular dynamics simulations using ab initio fitted interactions and generic force fields

Abstract

Structures and dynamical properties of carbon dioxide (CO2) molecules in the zeolitic imidazolate frameworks-8 (ZIF-8) had been investigated by molecular dynamics (MD) simulations. The flexible ZIF-8 framework is modeled by generic AMBER force field which can remain the main structures of the frameworks without collapsing during the whole simulations. The MD simulations using the mixed generic force fields parameters (SIM II) and the ab initio fitted parameters (SIM III) for intermolecular interactions between CO 2 and framework are done for comparison. The self diffusion coefficient of CO2 molecules obtained from SIM III simulation is found less but more close to the experimental values than that obtained from SIM II simulation. The hydrogen atoms of HC-groups in the imidazolate ring have been indicated to be more favor adsorbent sites than the hydrogen atoms of H3C-groups in SIM III simulation, while they are equivalent in the SIM II simulation. Copyright © 2013 American Scientific Publishers.