A density functional theory study of the anthracene anion

The optimized geometries, harmonic vibrational frequencies, and absolute energies of anthracene and anthracene− were determined using density functional methods. Adiabatic electron affinities (EAs) of 0.360, 0.274, 0.590 and 0.530 eV were calculated using B3LYP/cc-pVDZ, BLYP/cc-pVDZ, BP86/cc-pVDZ and B3LYP/6-31+G*, respectively. The EAs are in good agreement with experiment, with the B3LYP/6-31+G* value matching the experimental value and the BP86/cc-pVDZ value displaying an absolute error of only 0.060 eV. Accurate predictions of experimental parameters were obtained using all three functionals. Single point calculations using the aug-cc-pVDZ, cc-pVTZ and aug-cc-pVTZ basis sets are included to investigate the effect of basis set expansion and diffuse functions on the computed EAs. The excellent performance of density functional theory (DFT) for this system contrasts with poor results generated using Hartree–Fock theory.