Functionals with large amounts of FE tend to worsen the description of excimer binding across the four tested systems. Functionals with 20% FE yield the smallest errors in D e for each excimer, but the errors do increase with system size, yielding errors that range from -70.8 to 3.4%. Functionals containing 75% FE (-97.5 to -41.7% error range in D e ) are comparable to those with 0% (-97.4 to -22.7% error range in D e ) which are wellknown to produce large errors for excited states and offer no exception here. GGAs are therefore not explored in the benchmarking study of the following section. The poor performance associated with 37.5-75% FE, however, is somewhat surprising given that global hybrids with large amounts of FE generally describe CT and other long-range excitation effects better than smaller amounts of FE. High percentages of FE combined with PBE exchange and correlation appear to improve the description of r e in larger excimers. However this improved description of r e cannot overcome the poor description of D e by these functionals.