Mean Residence Time of CO₂ Molecules in Flexible ZIF-8 Cages Explored by Molecular Dynamics Simulations

The adsorption sites and diffusion mechanism of CO₂ molecules in the flexible Zn(MeIM)₂ (MeIM=2-methylimidazole) (ZIF-8) have been investigated by grand canonical Monte Carlo and molecular dynamics simulations. A reasonable time correlation function is for the first time constructed to explore the mean residence time of CO₂ molecules in the ZIF-8 cages, suggesting that CO₂ molecules can remain in the same cage for up to several tens of picosec-onds. Furthermore, we find that the mean residence time almost linearly increases with the increasing pressure (or loading) at 273 and 298 K.