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.