In this paper, we apply the extended tight-binding method self-consistently to investigate the electronic structure of the ideal (100) surface of diamond. Our calculation identifies surface states in the conduction band and predicts core shifts for surface atoms. The energy distribution across the surface Brillouin zone is analyzed in terms of the orbital densities of states. It is concluded that the extended tight-binding method can be successfully used for investigating surface electronic properties. © 1977 The American Physical Society.