Quantitative Simulations of Siloxane Adsorption in Metal–Organic Frameworks

Abstract

We present a transferable force field (FF) for simulating the bulk properties of linear and cyclic siloxanes and the adsorption of these species in metal−organic frameworks (MOFs). Unlike previous FFs for siloxanes, our FF accurately reproduces the vapor−liquid equilibria of each species in the bulk phase. The quality of our FF combined with the Universal Force Field using standard Lorentz−Berthelot combining rules for MOF atoms was assessed in a wide range of MOFs without open metal sites, showing good agreement with dispersion-corrected density functional theory calculations. Predictions with this FF show good agreement with the limited experimental data for siloxane adsorption in MOFs that is available. As an example of using the FF to predict adsorption properties in MOFs, we present simulations examining entropy effects in binary linear and cyclic siloxane mixture coadsorption in the large-pore MOF with structure code FOTNIN.

Machine Learning Models for Predicting Molecular Diffusion in Metal–Organic Frameworks Accounting for the Impact of Framework Flexibility

“…Methods have recently been introduced allowing creation of structural models containing point defects in large libraries of MOFs that will make simulations of this kind more feasible than in the past . Similarly, in the most interesting examples, it would be productive to assess the quality of generic FFs, a task that can be accomplished by performing systematic comparisons between molecular adsorption energies calculated with an FF and calculated with higher-level methods such as dispersion-corrected DFT. − …”

“… 60 Similarly, in the most interesting examples, it would be productive to assess the quality of generic FFs, a task that can be accomplished by performing systematic comparisons between molecular adsorption energies calculated with an FF and calculated with higher-level methods such as dispersion-corrected DFT. 61 − 64 …”