Metal precursors RuCp2 and CoCp2 are then adsorbed at the two terminations of Si(100) with the more favourable horizontal interaction mode, as described in our earlier studies . The computed adsorption energies on H-terminated and NHx-terminated Si(100) substrates are summarized in Table and the configurations are shown in Figure . CoCp2 has stronger adsorption strength than RuCp2 on both substrates, which are -0.98eV on H-Si(100) and -0.87eV on NHx-Si(100) for CoCp2 and -0.37eV on H-Si(100) and -0.67eV on NHx-Si(100) for RuCp2. This difference is analogous to the results on NHx-terminated Ru(100) and Co(100) surfaces in our previous studies , where the computed adsorption energies for CoCp2 and RuCp2 are -1.67eV and -0.79eV, respectively. Upon adsorption on both H:Si(100) surface and NHx-Si(100) surface, the Co-C distances are in the range of 2.05Å to 2.08Å, while the Ru-C distances are in the range of 2.18Å to 2.19Å. In the gas-phase metal precursors, CoCp2 has a Co-C distance ranging from 2.08Å to 2.10Å and RuCp2 has an Ru-C distance 2.18Å. There are no significant distortions to the structure of the metal precursors upon interaction at this H-terminated Si (100) surface.