A classical molecular dynamics study of the vibrational dynamics of the H/C(111)-(1x1) system

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. (C) 1998 Elsevier Science B.V.