Equilibrium configuration of bond-centeredH0in GaAs

The equilibrium structure of neutral interstitial hydrogen near the bond-centered site in GaAs is calculated at the ab initio Hartree-Fock level in the cluster ${\mathrm{HGa}}_4$ ${\mathrm{As}}_4$ ${\mathrm{H}}_{18}$ using a split-valence basis set and ab initio pseudopotentials for the core orbitals. The calculated spin densities and various other properties agree well with the muon-spin-rotation and level-crossing resonance-spectroscopy measurements.