CRITICAL-ASSESSMENT OF DENSITY-FUNCTIONAL METHODS FOR STUDY OF PROTON-TRANSFER PROCESSES - (FHF)(-)

Most variants of density functional theory (DFT) yield a proton transfer barrier in (F...H...F)(-) which is considerably smaller than the best correlated conventional ab initio results, with a large polarized basis set. The agreement is best for DFT methods with nonlocal exchange and correlation functionals, especially hybrid approaches which mix Hartree-Fock and Slater exchange. For all methods investigated, there is a close inverse relationship between the height of the barrier and the optimized r(FH).