We present detailed results of ab initio pseudopotential calculations for equilibrium atomic geometry and chemical bonding on the arsenic terminated GaAs(001)-β2(2×4) surface. Of particular note is our finding that there are two distinct Ga-As bond lengths between the first and second layers. This feature is due to the presence of both threefold and fourfold coordinated Ga atoms in the second layer. Our results add significantly to the information available from recent first-principles calculations, and from scanning tunneling microscopy, reflection high-energy electron diffraction, and low-energy electron diffraction analyses. © 1996 The American Physical Society.

• Received 17 January 1996

DOI:https://doi.org/10.1103/PhysRevB.53.12589