Interpreting tunneling spectroscopic maps of a dinuclear Co(II) complex on gold

Abstract

Scanning tunneling microscope data from a dinuclear Co(II) complex adsorbed on Au(111) are analysed using density functional theory calculations. We find that the interaction with the substrate substantially changes the geometry of the non-planar molecule. Its electronic states, however, remain fairly similar to those calculated for a gas-phase molecule. The calculations reproduce intriguing contrasts observed in experimental maps of the differential conductance dI/dV and reveal the relative importance of geometric and electronic factors that impinge on the image contrasts. For a meaningful comparison, it is important that the calculations closely mimic the experimental mode of measurement.