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.