Hybrid Monte Carlo Simulations Combined with a Phase Mixture Model to Predict the Structural Transitions of a Porous Metal-Organic Framework Material upon Adsorption of Guest Molecules

摘要

Anisotropic isobaric/isothermal molecular dynamics (MD) and grand canonical Monte Carlo (GCMC) techniques are combined in a hybrid scheme to get an osmotic Monte Carlo approach able to deal with a guest-assisted structural transition of a metal organic framework (MOF) porous solid corresponding to a large reversible breathing of its structure. This strategy based on (i) a consideration of a more general expression of the partition functions and (ii) a rigorous homogenization of the MD and MC parts allows us to capture the structural transition of the MIL-53(Cr) MOF-type solid in relation to the CO2 pressure. Further, we show that combining this revisited hybrid osmotic Monte Carlo (HOMC) approach to a newly developed "phase mixture" model, which is based on the existence of a pressure domain where several structural forms of MIL-53(Cr) are present, is an efficient way to accurately predict the adsorption behavior of this solid in the whole range of pressures.