Adsorption and scanning-tunneling-microscope imaging of benzene on graphite andMoS2

We report ab initio total energy and electronic structure calculations for benzene physisorbed on graphite and ${\mathrm{MoS}}_2$. Our results constitute the first detailed ab initio investigation of the states through which tunneling occurs in the scanning tunneling microscope (STM) through an insulating molecule. At low voltages the density of states near the Fermi energy some way from the surface is dominated by a weak admixture of molecular states into the substrate states; the resulting STM images reflect the details of the molecule-substrate interaction. At higher voltages, images of molecular states are obtained.