CO₂ adsorption in Fe₂(dobdc): A classical force field parameterized from quantum mechanical calculations

Carbon dioxide adsorption isotherms have been computed for the metal-organic framework (MOF) Fe₂(dobdc), where dobdc^4- = 2,5-dioxido-1,4-benzenedicarboxylate. A force field derived from quantum mechanical calculations has been used to model adsorption isotherms within a MOF. Restricted open-shell Møller-Plesset second-order perturbation theory (ROMP2) calculations have been performed to obtain interaction energy curves between a CO₂ molecule and a cluster model of Fe ₂(dobdc). The force field parameters have been optimized to best reproduced these curves and used in Monte Carlo simulations to obtain CO ₂ adsorption isotherms. The experimental loading of CO₂ adsorbed within Fe₂(dobdc) was reproduced quite accurately. This parametrization scheme could easily be utilized to predict isotherms of various guests inside this and other similar MOFs not yet synthesized.