Path and energy dependence of CH₄ dissociation on Pd(110) and Pd(320)

Dissociation of methane on Pd(110) and Pd(320) is investigated using molecular dynamics simulations and statistical analysis of excitations of vibrational modes of the molecule. Simulations are made by varying translational energy and excitations of vibrational stretching (ν₁) and bending (ν₂) modes of methane. The role of these factors in dissociation is found to depend on the adsorption path in a rather complicated way. Especially, different vibrational modes seem to facilitate dissociation at different adsorption site and for different orientation of the molecule. Statistical analysis of excitations of vibrational modes indicate that dissociation is governed at low vibrational temperatures by bending modes and on higher temperatures by stretching mode. Translational energy is still found to be more efficient activator of dissociation than vibrational energy.