Elucidation of\nCO Oxidation and CO<sub>2</sub> Desorption\nDynamics on Pt(111) by van der Waals DFT Calculations: Hyperthermal\nKinetic Energy, Sharp Desorption Angle, and Excited Vibrational States

We have studied the CO oxidation process and CO<sub>2</sub> desorption\ndynamics on Pt(111) using density functional theory (DFT) within the\ngeneralized gradient approximation (GGA) and van der Waals (vdW) functionals.\nThe calculated potential energy surfaces indicate that the most kinetically\nfavorable pathway for CO oxidation is the hexagonal close-packed (HCP)\npathway, where the oxidation is initiated by the movement of an O\natom at the HCP site toward the adsorbed CO. The ab initio molecular\ndynamics (AIMD) simulation revealed that one of a few combinations\nof the GGA and vdW functionals provides the most quantitative explanation\nof the experiments regarding the distribution of the kinetic energy,\ndesorption angle, and OCO bending vibration of the desorbed CO<sub>2</sub>. The good agreement is the result of an accurate description\nof the reactant (CO + O) and product (CO<sub>2</sub>) in both the\nchemisorbed and physisorbed states. The AIMD simulation also clearly\nshows that the CO<sub>2</sub> is desorbed in vibrational excited states\nwith energy transfer between the bending and symmetric stretching\nmodes.