Theoretical study of benzene and pyridine STM-induced reactions on copper surfaces

Density functional theory calculations are used to determine the adiabatic reaction pathways of STM-induced reactions of benzene and pyridine molecules on Cu(100), Cu(110) and Cu(111). The studied reactions are rupture of the molecular ring as well as dehydrogenation of the molecules. In order to establish the final fragments of the reactions, the inelastic electron tunneling spectra of the molecules are analyzed and rationalized in terms of the electronic structure of the system. Besides vibrational excitation, the impinging electron confers on the molecule a dynamical evolution that depends on the capacity of the system to damp the excess energy. We predict that in the limit of heavy fragments, and hence for the heaviest isotopes, the STM bias voltage will match the computed adiabatic barriers