The results of first-principles calculations were reported for the adsorption of As2 molecules on the stable surface reconstructions of the (001) surface. This included adsorption paths and barriers for strongly bound sites. It was shown that a novel chemisorption state acted, together with an intermediate physisorbed plateau in the total energy, to hold the As2 molecules near to the surface and funnel them into strong bonding sites during epitaxial growth. This state could explain the transition from the β2(2 x 4) to the c(4 x 4) reconstruction under low-temperature and highly As-rich conditions.

Arsenic Dimer Dynamics during MBE Growth - Theoretical Evidence for a Novel Chemisorption State of As2 Molecules on GaAs Surfaces C.G.Morgan, P.Kratzer, M.Scheffler: Physical Review Letters, 1999, 82[24], 4886-9