Energy-Minimization Approach to the Atomic Geometry of Semiconductor Surfaces

The (110) surface atomic geometries of GaAs and ZnSe and of 2 1 reconstructed (111) surface of Si are calculated by minimizing the total energy of the electron-ion system. The corresponding reductions in total energy between the relaxed and unrelaxed surfaces are calculated to be - 0. 51, - 0. 30, and - 0. 37 eV per surface atom, respectively. Subsurface relaxations are generally found to make a very small (0. 02 eV) contribution to the reduction in total energy.