Application of screened hybrid density functional theory to ammonia decomposition on silicon

Screened hybrid exchange-correlation (XC) density functionals incorporating short-range exact exchange aid application of hybrid density functional theory to solids and surfaces. We explore screened hybrid XC functionals for a prototypical surface reaction, namely, adsorption and dissociation of ammonia on silicon. Screened hybrids are found to improve upon standard semilocal functionals for the dissociation barrier on Si₉H₁₂, reproducing accurate complete basis set extrapolated CCSD(T) results. Similar trends are found for realistic periodic Si(100)-2 × 2 surfaces. Screened hybrids also better reproduce experimental results for the relative barriers to different dissociation pathways. While the tested hybrid functionals tend to overestimate molecular adsorption energies, their good performance for kinetics motivates further exploration of screened exchange in surface chemistry.