Theoretical studies of molecule-surface scattering

Quasi-classical trajectory studies of hydrogen molecule - copper surface interaction were performed employing a modified semiempirical LEPS potential. The surface is treated as rigid (phononless) and corrugated. Dissociative adsorption and selective adsorption were observed. The roughness of the molecule surface interaction potential, the normal incident energy of the molecular projectile, and the position of approach are the major factors that cause the dissociation. The energy dependence of the selective adsorption was investigated in detail. Diffractions appear in the scattering processes due to the corrugation of the surface and the parallel momentum of the molecular projectile is conserved. Quantum mechanical bound state calculations were carried out to study hydrogen molecule copper surface selective adsorption employing the same LEPS potential. The rotationally or vibrationally mediated selective adsorptions arise from the excitations of the internal states of the molecule. For the incident energies below 300 meV, the rotation mediations are dominant in the resonance scattering, whereas the resonance states that arise from the vibration mediations frequently appear above that energy. Good agreement is found between the quantal and classical results on the energies of the selective adsorbed states and other physical quantities related to the states above the potential barrier where tunneling effect is not important