Tuning in on single molecular states: adsorption sites and STM images of maleic anhydride on Si(1 0 0)

We show that, counterintuitively, maleic anhydride on Si(1 0 0) surfaces adsorbs on inter-row sites. Our first principles simulations establish that this site is preferred for coverages of less than 1/8 ML. In simulations of scanning tunnelling images we establish also, that the corrugation is enhanced by more than 0.5 إ, if a single molecular state contributes to the tunnelling current. The combined evidence of images and simulations allows the conclusion that experiments in fact reveal the geometry of single molecular wavefunctions.