Chemisorption sites and reaction pathways for acetylene on Si(111)-(7x7)

The interaction between the acetylene molecule (C2H2) and the Si(1 1 1)-(7 x 7) surface is studied using both ab initio and empirical methods. Several possible chemisorption configurations are explored, which may be helpful to rationalize recent experimental results. The kinetics of the chemisorption process is also studied by means of accurate ab initio calculations, and low-energy paths leading to stable configurations are identified. It is shown that large-scale calculations based on the use of semi-empirical potentials, in tight cooperation with ab initio calculations, can be an efficient tool to achieve a broad overview of the chemisorption reactions of molecules occurring on complex semiconductor surfaces.