The selection of the functional in DFT is
crucial for correctly exploring the properties and reaction mechanisms
of chemical reactions.
Considerable effort has been
invested to overcome this severe deficiency of DFT.
Grimme9
has proposed a new semiempirical functional by introducing
atom-pairwise dispersion corrections to the generalized gradient
approximation (GGA) part of the B97 functional.
Zhao and Truhlar10-13 have recently developed the M06 family of local
(M06-L) and hybrid (M06,M06-2X) meta-GGA functionals that
show promising performance for studying main group thermochemistry,
kinetics, noncovalent interactions, excited states, and
transition elements.