Calculations of the neutral and charged states of the {H,C} pair in silicon

We have performed systematic studies of the {H,C} pair in Si with molecular clusters and supercells at various levels of Hartree-Fock, post Hartree-Fock, and density functional theory, within and beyond the local density approximation. We found that, in this particular case, electron correlation plays an important role in determining the equilibrium structure. For both {H,C}⁰ and {H,C}⁺ states, the bond-centered configuration C-H···Si is the most stable while the H-C···Si configuration is stable in the -1 charge state. The electronic structures and metastable states are also discussed.