Get access

Performance assessment of density-functional methods for study of charge-transfer complexes



Various density functionals are applied to a number of weakly bound intermolecular π–π charge-transfer (CT) complexes. Most functionals, including the recently developed mPWPW91 and mPW1PW91, grossly underestimate experimental excitation energies; good agreement is obtained only with the half-and-half hybrid BH&HLYP functional. PW91PW91 provides the best agreement with intermolecular distances measured in crystal, while the BH&HLYP values are about 0.1 Å too long. Various hybrid functionals with nonlocal exchange correction provide binding energies that compare favorably with the experimental heats of formation measured in solution. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 623–631, 2003