Theoretical Study of the Adsorption of Acetylene on the Si(001) Surface

Recent STM measurements and electronic structure calculations have revealed that the Si(001)/acetylene surface is far more complex than previously assumed, with there being at least three different binding arrangements of an acetylene molecule on the surface. In the present study density functional theory with slab models and periodic boundary conditions are used to study the adsorption of acetylene on the Si(001) surface. Nine different local potential energy minima, including three not previously described, are characterized. The relative stability of the two lowest energy structures is found to reverse with increasing surface coverage. The minimum energy pathways between selected pairs of local minima are calculated