title: Probing gas adsorption in MOFs using an efficient ab initio widom insertion Monte Carlo method.
abstract: We propose a novel biased Widom insertion method that can efficiently compute the Henry coefficient, KH, of gas molecules inside porous materials exhibiting strong adsorption sites by employing purely DFT calculations. This is achieved by partitioning the simulation volume into strongly and weakly adsorbing regions and selectively biasing the Widom insertion moves into the former region. We show that only few thousands of single point energy calculations are necessary to achieve accurate statistics compared to many hundreds of thousands or millions of such calculations in conventional random insertions. The methodology is used to compute the Henry coefficient for CO2, N2, CH4, and C2H2in M-MOF-74(M = Zn and Mg), yielding good agreement with published experimental data. Our results demonstrate that the DFT binding energy and the heat of adsorption are not accurate enough indicators to rank the guest adsorption properties at the Henry regime. © 2016 Wiley Periodicals, Inc.
authors.affiliation: KAIST, Department of Chemical and Biomolecular Engineering, Daejeon, South Korea.
authors.forename: Youhan
authors.initials: Y
authors.lastname: Lee
authors.affiliation: SIMAP, CNRS, Univ. Grenoble Alpes, Grenoble, France.
authors.forename: Roberta
authors.initials: R
authors.lastname: Poloni
authors.affiliation: KAIST, Department of Chemical and Biomolecular Engineering, Daejeon, South Korea.
authors.forename: Jihan
authors.initials: J
authors.lastname: Kim
keywords: adsorption; binding sites; density functional theory; metal organic frameworks; widom insertion