Density functional theory studies of the quadrupole moments of benzene and naphthalene

The molecular quadrupole moments of benzene and naphthalene are calculated using a range of ab initio and density functional methods, with basis sets as large as aug-CC-PVTZ for benzene and CC-PVTZ for naphthalene. The quadrupole moments calculated using Hartree-Fock wavefunctions are lower than the experimentally determined values, and all DFT values are higher than the experimental values. The use of the hybrid B3P86 and B3PW91 functionals, with a large basis set, produce quadrupole moments which are within experimental error for these two small aromatic molecules.