London Dispersion Corrections to Density Functional Theory for Transition Metals Based on Fitting to Experimental Temperature-Programmed Desorption of Benzene Monolayers

Standard
implementations of generalized gradient approximation
(GGA)-based density functional theory (DFT) describe well strongly
bound molecules and solids but fail to describe long-range London
dispersion or van der Waals (vdW) attraction interactions that are
important in molecular crystals and two-dimensional solids. To provide
accurate values for the vdW distance and energies for the metals Cu,
Ag, Au, Ni, Pd, and Pt, we determined empirical vdW corrections to
Perdew, Burke, and Ernzerhof (PBE) DFT by fitting the experimental
adsorption enthalpies measured by temperature-programmed desorption
(TPD) from benzene monolayers by Campbell and co-workers (J. Phys. Chem. C 2016, 120, 25161−25172). Benzene
physisorbed to these metals without chemical reaction; therefore,
we consider the bonding to be vdW. We use the low gradient form for
the vdW corrections, EvdW‑LG =
−C6LG/[R6 + RvdwLG6] with just two
parameters per atom (C6LG and RvdwLG). This LG form leads to negligible changes
in bond distances and angles, so adjusting the parameters should not
sacrifice accuracy for the bonding interactions. We demonstrate that
the parameters fitted to benzene also describe well the physisorption
enthalpies for other hydrocarbons (naphthalene, cyclohexane, methane,
ethane, and propane) on Pt. We also report low gradient vdW correction
parameters for the noble gases that fit the equilibrium lattice parameter
and heat of vaporization of the crystals.