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. (C) 2004 Elsevier B.V. All rights reserved.