Performance of the OPBE exchange-correlation functional

In a recent evaluation of density functional theory (DFT) functionals OPBE, which combines Handy's optimized exchange (OPTX) with the PBE correlation, was shown to correctly predict the spin states (singlet through sextet) of seven different iron complexes (2004, J. Phys. Chem. A, 108, 5479). The present study provides a further test of OPBE as well as that of the OPerdew and OLYP functionals, in which OPTX is combined with the Perdew and LYP correlations, respectively. These three are compared to other pure DFT functionals for their performance in calculating the atomization energies for the G2-set of up to 148 molecules, six reaction barriers of S_N2 reactions, geometry optimizations of 19 small molecules and four metallocenes, and zero-point vibrational energies for 13 small molecules. OPBE performs exceptional well in all cases.