Reduced partition function ratios of hydrogen species adsorbed on platinum cluster Pt19 studied by density functional theory

Geometry optimization and estimation of H/D reduced partition function ratios (RPFRs) of Pt₁₉–H, Pt₁₉–H⁺, Pt₁₉–H₂, and Pt₁₉–H₂⁺ models of hydrogen species adsorbed on surfaces of metallic platinum particles, were carried out based on the density functional theory. Two types of optimized structures were obtained for Pt₁₉–H and Pt₁₉–H⁺, and three for Pt₁₉–H₂ and Pt₁₉–H₂⁺. Stabilization energy consideration suggested that the most probable structure for Pt₁₉–H and Pt₁₉–H⁺ is the one in which H/H⁺ is bonded to a Pt atom, and that for Pt₁₉–H₂ and Pt₁₉–H₂⁺ is the one in which two H/H⁺s are bonded to two adjacent Pt atoms with no direct bonding between the two H/H⁺s. The value of RPFR obtained for those structures ranged from 3.9303 to 4.4014 at 25 °C. Interaction between two adjacent H–Pt bonds seems to slightly enhance the mutual RPFR values.