Novel electronic properties of a potassium overlayer on Si(001)-(2×1)

We report self-consistent, geometry-optimized, total electronic energy calculations for a K overlayer on a Si(001)-(2×1) surface. Our theory for metallization of the overlayer and dimensionality of collective excitations is different from previous suggestions and can successfully account for the experimental findings about this system. The metal-insulator transition is proposed to have its origin in active dangling bonds and not in the conventional Mott transition. We find a strong ionic type of binding between the overlayer and the substrate. © 1986 The American Physical Society.