Molecular SCF calculations to model (111) surface states and relaxation of diamond

Ab-initio SCF-MO computations in an STO-3G Gaussian basis on a molecular system, designed to model a carbon atom on the (111) surface of diamond, predict that the danglingbond carbon relaxes about 0.10 Å toward the bulk from its position on an extension of the diamond lattice. The dangling bond carbon cation relaxes Inward 0.30 Å, while the anion relaxes outward 0.10 A. Tentative ways to describe the dangling bond in terms of computed quantities are presented.