Evaluation of Force Field Performance for High-Throughput Screening of Gas Uptake in Metal–Organic Frameworks

High-throughput computational screening
is an increasingly useful
approach to identify promising nanoporous materials for gas separation
and adsorption applications. The reliability of the screening hinges
on the accuracy of the underlying force fields, which is often difficult
to access systematically. To probe the accuracy of common force fields
and to assess the sensitivity of the screening results to this accuracy,
we have computed CO2 and CH4 gas adsorption
isotherms in 424 metal–organic frameworks using ab
initio force fields and evaluated the contribution of electrostatic,
van der Waals, and polarization interactions on the predicted gas
uptake and the adsorption site probability distributions. While there
are significant quantitative differences between gas uptake predicted
by standard (generic) force fields (such as UFF) and ab initio force fields, the force fields predict similar ranking of the MOFs,
supporting the further use of generic force fields in high-throughput
screening studies. However, we also find that isotherm predictions
of standard force fields may benefit from significant error cancellation
resulting from overestimation of dispersion and neglect of polarization;
as such, caution is warranted, as this error cancellation may vary
among different classes of materials.