The electronic stmcture of lattice vacancies on the STM image of a graphite surface

Using the extended Hückel molecular orbital method and cluster models, we have studied the STM image which shows the effect of ion impacts on a graphite surface. Our results show that lattice vacancies create an enhancement of the charge density in the atoms directly surrounding them, implying their enhanced chemical reactivity. Thus, our results imply that either the lattice vacancies or an ion-induced chemical reaction of adsorbed molecules with the graphite lattice may be used to explain the STM image, and sometimes both may be used.