Multiscale Modeling of Water in Mg-MOF-74: From Electronic Structure Calculations to Adsorption Isotherms

We propose a force field model for the description of water adsorption in Mg-MOF-74 and assess its accuracy by performing a series of molecular simulations. The model is defined in terms of electrostatic, repulsive, and attractive contributions, the parameters of which are independently derived from first-principles calculations. The force field accurately reproduces the most relevant part of the ab initio potential energy surface as well as pair-correlation functions obtained from molecular dynamics (MD) simulations. The model is further applied for calculating adsorption properties and isotherms within Monte Carlo and MD simulations. The obtained force field shows an improved description of the experimental adsorption isotherms compared to the standard water models, which allows us to expect its good performance for other large-scale simulations of water in Mg-MOF-74.