title: First-principles Hubbard U approach for small molecule binding in metal-organic frameworks.
abstract: We apply first-principles approaches with Hubbard U corrections for calculation of small molecule binding energetics to open-shell transition metal atoms in metal-organic frameworks (MOFs). Using density functional theory with van der Waals dispersion-corrected functionals, we determine Hubbard U values ab initio through an established linear response procedure for M-MOF-74, for a number of different metal centers (M = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu). While our ab initio U values differ from those used in previous work, we show that they result in lattice parameters and electronic contributions to CO2-MOF binding energies that lead to excellent agreement with experiments and previous results, yielding lattice parameters within 3%. In addition, U-dependent calculations for an example system, Co-MOF-74, suggest that the CO2 binding energy grows monotonically with the value of Hubbard U, with the binding energy shifting 4 kJ/mol (or 0.041 eV) over the range of U = 0-5.4 eV. These results provide insight into an approximate but computationally efficient means for calculation of small molecule binding energies to open-shell transition metal atoms in MOFs and suggest that the approach can be predictive with good accuracy, independent of the cations used and the availability of experimental data.
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720, USA.
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Mann
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA.
authors.forename: Kyuho
authors.initials: K
authors.lastname: Lee
authors.affiliation: Theory and Simulation of Materials (THEOS), École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors.forename: Matteo
authors.initials: M
authors.lastname: Cococcioni
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720, USA.
authors.forename: Berend
authors.initials: B
authors.lastname: Smit
authors.affiliation: Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Neaton