Proton-transfer reaction of toluene on Si(100) surface

The chemisorption of toluene on the Si(100) surface is studied via first principles calculations. We find that the most stable configuration is a dissociated one, in which a C-H bond of the methyl group is cleaved and the loose hydrogen is bonded to the silicon surface; a detailed analysis based on the use of the maximally-localized Wannier functions indicates that this process can be described as a proton transfer reaction. Possible reaction pathways leading from one stable adsorption configuration to another and to the dissociation of the toluene molecule on the Si surface have been investigated; in particular the one involving the abstraction of an H atom from the methyl group has been found to be activated, with an energy barrier of about 1.4 eV. Our results are compared with recent experimental measurements.