An embedded cluster study of dimer buckling on the Si(100) surface

Both ${\mathrm{Si}}_{\mathrm{9}}{\mathrm{H}}_{\mathrm{12}}$ and ${\mathrm{Si}}_{\mathrm{15}}{\mathrm{H}}_{\mathrm{16}}$ cluster models for the Si(100) surface were studied using the Hartree–Fock molecular-orbital method and density functional theory. Our investigation shows that the ground state of the Si(100) surface consists of buckled dimers, contrary to the results of a number of previous embedded cluster calculations, but in agreement with some recent slab calculations. The relaxation constraints used in previous embedded cluster studies probably do not model the relaxation of the Si(100) surface layers adequately.