The anthracene excimer is slightly more stable than the naphthalene excimer, with an SCS-CC2/CBS (3,4) dissociation energy of 28.40 kcal/mol at a larger equilibrium monomer separation of 3.18 Å (Fig. ). The herein tested TD-DFAs uniformly underbind the anthracene excimer with absolute errors in D e between 5.71 and 21.52 kcal/mol and overestimate r e by between 0.05 and 0.43 Å. Trends in functional performance are similar to those of the naphthalene excimer, although with larger errors in D e . Each functional predicts a smaller excimer dissociation energy for the anthracene excimer than it does for the naphthalene excimer, so comparison with the larger reference value for the anthracene excimer results in larger errors for D e (20-76%).