Force Field Development from Periodic Density Functional Theory Calculations for Gas Separation Applications Using Metal Organic Frameworks
We present accurate force fields developed from density functional theory (DFT) calculations with periodic boundary conditions for use in molecular simulations involving M2(dobdc) (M MOF 74; dobdc4 2,5 dioxidobenzenedicarboxylate; M Mg, Mn, Fe, Co, Ni, Zn) and frameworks of similar topology. In these systems, conventional force fields fail to accurately model gas adsorption due to the strongly binding open metal sites. The DFT derived force fields predict the adsorption of CO2, H2O, and CH4 inside these frameworks much more accurately than other common force fields. We show that these force fields can also be used for M2(dobpdc) (dobpdc4 4,4' dioxidobiphenyl 3,3' dicarboxylate) an extended version of MOF 74, and thus are a promising alternative to common force fields for studying materials similar to MOF 74 for carbon capture applications. Furthermore, it is anticipated that the approach can be applied to other metal organic framework topologies to obtain force fields for different systems. We ha.