For the pyrene excimer, most D3(BJ)-corrected functionals underbind the system with absolute deviations in the range of 0.14-10.28 kcal/mol (0.4 to 31% error) for D e and 0.01-0.10 Å (0.3 to 3% error) for r e [Figure ]. Dispersion corrections reduce underestimation errors of uncorrected functionals but even the closest methods fail to reliably bind the pyrene excimer.