Adsorption energies on extended surfaces with CCSD(T) quality: ethylene on Si(001)

We present a theoretical benchmark calculation for the prototypical surface chemical reaction of ethylene on silicon(001). State-of-the-art coupled cluster calculations with periodic boundary conditions (CCSD(T)pbc) are carried out on three stationary points of the potential energy surface carefully studying the convergence of all computational parameters. The comparison to a set of commonly used density functionals show two situations along the reaction coordinate. The reaction energy is quite well reproduced with most density functionals, dispersion-corrected hybrid functionals being the most accurate as often stated for adsorption of organic molecules on semiconductor surfaces. However, the reaction barriers show large deviations of around 50% compared to the benchmark value which requires more investigations in the future. We hope to spark these investigations and provide a starting point for more theoretical benchmark studies on surface chemical reactions with larger molecules in the future.