Adsorption of benzene on Si(100) from first principles

Abstract

Adsorption of benzene on the Si(100) surface is studied from first principles. We find that the most stable configuration is a $\mathrm{tetra}-\sigma -\mathrm{bonded}$ structure characterized by one C-C double bond and four C-Si bonds. A similar structure, obtained by rotating the benzene molecule by 90°, lies slightly higher in energy. However, rather narrow wells on the potential-energy surface characterize these adsorption configurations. A benzene molecule impinging on the Si surface is most likely to be adsorbed in one of three different $\mathrm{di}-\sigma -\mathrm{bonded},$ metastable structures, characterized by two C-Si bonds, and eventually converts into the lowest-energy configurations. These results are consistent with recent experiments.