Semiclassical interatomic potential for carbon and its application to the self-interstitial in graphite

A semiclassical interatomic potential for carbon is discussed which is based on the proximity cell (the Wigner-Seitz cell) around each atom. It introduces three internal degrees of freedom per atom, representing the magnitude and direction of the p orbital that is not involved in sp hybridization. Its direct interpolation between sp 2 and sp 3 configurations combined with good elastic properties allows its use on problematic defects, such as the interplanar interstitial in graphite, which is given as an example.