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 Pt-19-H, Pt-19-H+, Pt-19-H-2, and Pt-19-H-2(+) 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 Pt-19-H and Pt-19-H+, and three for Pt-19-H-2 and Pt-19-H-2(+). Stabilization energy consideration suggested that the most probable structure for Pt-19-H and Pt-19-H+ is the one in which H/H+ is bonded to a Pt atom, and that for Pt-19-H-2 and Pt-19-H-2(+) 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 degrees C. Interaction between two adjacent H-Pt bonds seems to slightly enhance the mutual RPFR values.