Interpolating DFT Data for 15D Modeling of Methane Dissociation on an fcc Metal

Detailed simulation of reactions occurring on and with the surfaces of crystalline materials usually require a continuous representation of the potential energy surface that describes the adsorbate–surface interaction. Only a few techniques are available to describe interactions with polyatomic adsorbates that respect all of the symmetries of the interactions. The modified Shepard interpolation has recently been reformulated to ensure symmetries are rigorously imposed. In this work, the modified Shepard interpolation is used to construct a 15D potential energy surface for the reaction of methane with the {100} surface of a face-centered cubic metal, in the Born--Oppenheimer static surface (BOSS) approximation. The energy of the system is calculated using density functional theory (DFT), and the geometries around which the potential is expanded are selected by quasi-classical trajectory calculations. The energy of the resulting continuous potential energy surface exactly matched the DFT energy at these points; there is no fitting error. It is demonstrated that the classical reaction probability converges with a reasonable number of interpolation points for this 15D system.