Electronic structure and interlayer binding energy of graphite

This doctoral dissertation addresses the experimental and theoretical elucidation of the geometric and electronic structure and the interlayer binding energy of graphite. The synthetic form of graphite, highly oriented pyrolytic graphite (HOPG), has been used as a standard for scanning tunneling microscope (STM) calibration for over a decade because of the relative ease of imaging in air and vacuum coupled with the known carbon-carbon distances. Most images show only three of the six carbon atoms in a given six-membered ring. This observation has been rationalized in several ways, although no entirely satisfactory explanation exists yet. In this work, a new interpretation of the graphite STM image is proposed. This interpretation is based on (1) an analysis of small asymmetries in STM images of HOPG obtained in our lab and from the literature, (2) computations of the electronic structure and STM image of graphite using density functional theory (DFT), and (3) high-resolution powder x-ray diffraction (XRD) studies.;The possible effects in graphite's STM image of interlayer interactions motivated the second topic of this thesis. Here, we investigate the pi-pi interactions between polycyclic aromatic hydrocarbons (PAHs). Second order Moller-Plesset perturbation theory and density functional theory are used to probe the correlation among molecular size, binding energy, and molecular polarizability.;Finally, we describe a proof-of-principle for the operation of a new optical differential reflectance (ODR) technique that can be used to provide accurate measurement of the Van der Waals (VdW) interaction between PAHs and graphite.