Theoretical analysis of the oxygen insertion process in the oxidation reactions of H2O + H/Si(1 0 0) and 2H + H2O/Si(1 0 0): a molecular orbital calculation and an analysis of tunneling reaction

The reaction paths are analyzed, by an ab initio molecular orbital method, for the surface reaction systems 2H + H2O/Si(1 0 0)-(2×1) and H2O + H/Si(1 0 0)-(2×1), in which SiH2 species with one or two oxygen atom-inserted back bonds have been observed as stable reaction products. The following results are obtained: The initial energy for the former system is 87.97 kJ/mol higher than the highest transition state energies with the HF/6-31+G* level. In the latter system, the highest transition state is located 175.66 kJ/mol higher than the initial energy, and tunneling effect plays an important role.