Methanol adsorption on the Si(100)-2 × 1 surface: a first-principles calculation

The process of adsorption of methanol on a Si(100)-2 × 1 surface has been investigated theoretically, using density functional theory and a periodic boundary condition. The methanol adsorption on Si(100)-2 × 1 is known to be dissociative, resulting in hydrogen(methanol)–oxygen(surface) and oxygen(methanol)–silicon(surface) bond formation. Adsorption energies have been calculated here for five different surface sites for the methoxy fragment (top, bridge, cave, valley-bridge and pedestal). The top site was found to be energetically most favourable. Surface sites bridging Si atoms from the first and second atomic layers were found to be energetically equivalent to the top site. The effects of the position of the hydrogen fragment on the methoxy adsorption energy for the various adsorption sites were also investigated. These various hydrogen positions only influenced the adsorption energies marginally.