The Role of Partial Atomic Charge Assignment Methods on the Computational Screening of Metal-Organic Frameworks for CO2 Capture under Humid Conditions

Abstract

Molecular simulations were carried out to compare the results from two different partial charge assignment strategies: extended charge equilibration (EQeq), and density derived electrostatic and chemical (DDEC), by computing the Henry's law constants of CO2, H2O, and N2 for computation-ready, experimental (CoRE) MOFs. The Spearman's ranking correlation coefficient (SRCC) of the CO2/H2O selectivity rankings of MOFs with DDEC and EQeq charges based on the Henry's law constants showed that 8 out of the top 15 MOFs from screenings of MOFs with DDEC and EQeq charges were identical. We found that the most significant difference was observed in the adsorption energy for H2O molecules, which showed large contribution from electrostatic interactions in H2O adsorption energy, and for CO2 and N2 adsorption energies, van der Waals interaction energies played a major role.