  Increasing interest in sustainable synthesis of ammonia, nitrates, and urea
has led to an increase in studies of catalytic conversion between
nitrogen-containing compounds using heterogeneous catalysts. Density functional
theory (DFT) is commonly employed to obtain molecular-scale insight into these
reactions, but there have been relatively few assessments of the
exchange-correlation functionals that are best suited for heterogeneous
catalysis of nitrogen compounds. Here, we assess a range of functionals ranging
from the generalized gradient approximation (GGA) to the random phase
approximation (RPA) for the formation energies of gas-phase nitrogen species,
the lattice constants of representative solids from several common classes of
catalysts (metals, oxides, and metal-organic frameworks (MOFs)), and the
adsorption energies of a range of nitrogen-containing intermediates on these
materials. The results reveal that the choice of exchange-correlation
functional and van der Waals correction can have a surprisingly large effect
and that increasing the level of theory does not always improve the accuracy
for nitrogen-containing compounds. This suggests that the selection of
functionals should be carefully evaluated on the basis of the specific reaction
and material being studied.
