Fast and Accurate Electrostatics in Metal Organic Frameworks with a Robust Charge Equilibration Parameterization for High-Throughput Virtual Screening of Gas Adsorption

The charge equilibration (QEq) method has been parametrized to reproduce the ab-initio-derived electrostatic potential in a large and diverse training set of 543 metal organic frameworks (MOFs) containing the most popular Zn, Cu, and V structural building units (SBUs), 52 different organic carboxylate- and nitrogen-capped SBUs, and the 17 functional groups. The MOF electrostatic-potential-optimized charge scheme, or MEPO-QEq, was validated by evaluating the CO2 uptake and heats of adsorption in the 543 member training set and a nonoverlapping 693 member validation set. Compared with the results obtained from ab-initio-derived charges, the MEPO-QEq charges give Pearson (linear) and Spearman (rank-order) correlation coefficients of >0.97 for these two sets. MEPO-QEq enables near-ab-initio quality nonbonded electrostatic interactions to be evaluated using the fast QEq method for fast and accurate virtual high-throughput screening of gas-adsorption properties in MOFs.