First-principles calculations of atomic and electronic structure of the GaAs(110) surface

The (110) surface of GaAs is studied using self-consistent density-functional calculations implemented with soft ab initio pseudopotentials. The calculated atomic structure and relaxation energy of GaAs(110) surfaces are in good agreement with previous theoretical calculations and with measurements by low-energy electron diffraction. In addition, we have calculated the cleavage energy for this surface. We find a value of 1.22 eV per surface unit cell, which agrees nearly exactly with the experimentally measured energy of 1.21 eV per surface unit cell. To our knowledge this is the first comparison of density-functional calculations with experiment for the cleavage energy of any heteropolar semiconductor surface. We have also calculated the photoelectric threshold to be 4.94 eV, compared to the experimental values of 5.15--5.75 eV.