Simulation Procedure
First, the molecules N2, N, NH, NH2, and
NH3 are optimized in the gas-phase using each of the
three DFT functionals. The optimized molecules are then placed on the
(100) and (111) catalyst clusters at one of the preferential sites in
Figure 3. Each molecule is optimized separately at every possible
preferential site in order to determine the lowest energy position on
the catalyst. For N2 optimizations, that includes
testing end-on and side-on N-N configurations at each site. After
optimization, frequency calculations are run on the lowest energy
adsorption sites. This data is then compared between functionals and to
other theoretical and experimental benchmarks.