A classical molecular dynamics study of the vibrational dynamics of the H/C(111)-(1×1) system

Abstract

Vibrational dynamics of H atoms on C(111) surface was studied by classical molecular dynamics method with the use of a harmonic force field for the diamond lattice and of both harmonic and anharmonic potential for the C–H bond. Results of the calculations show a strong coupling of the C–C–H bending vibration to the the lattice modes. In addition to the experimentally observed band of the bending vibration at 1331 cm −1 the calculations predict a band at ca. 1000 cm −1 in the infrared spectrum of the system with the surface-parallel polarization. Results of the study show a strong dynamic anharmonicity of the large amplitude vibrations of hydrogen atoms. Simulations of the C–H stretching energy relaxation lead to values of the energy relaxation time close to those measured. The agreement is improved in the anharmonic model for the C–H bond potential. Results of the calculations point to the interaction between the C–H stretching vibration and the overtone of the C–C–H bending vibration as the main channel for the energy relaxation.