Calculation of the inelastic scanning tunneling image of acetylene on Cu(100)

A Green function linear combination of atomic orbitals technique is used to theoretically calculate the "inelastic" scanning tunneling microscope image of a C2H2 molecule adsorbed on Cu(100) and explain previous experimental results. Our analysis of the inelastic scattering process in terms of the orbitals shows that a destructive interference occurs in the inelastic scattering by the C-H bending modes. This results in a much smaller inelastic fraction due to the bending modes as compared to the stretching ones, and explains why the former cannot be observed experimentally.