Strongly correlated electrons on a silicon surface: Theory of a Mott insulator

We demonstrate theoretically that the electronic ground state of the potass ium-covered Si(111)-B surface is a Mott insulator, explicitly contradicting band theory but in good agreement with recent experiments. We determine th e physical structure by standard density-functional methods, and obtain the electronic ground state by exact diagonalization of a many-body Hamiltonia n. The many-body conductivity reveals a Brinkman-Rice metal-insulator trans ition at a critical interaction strength; the calculated interaction streng th is well above this critical value.