A hybrid density functional study of the first-row transition-metal monocarbonyls

The results of a systematic density functional study, carried out using a self-consistent hybrid approach including exact exchange contribution, on the all monocarbonyls of first-row transition metals, are reported. Geometries, harmonic wave numbers, and binding energies, obtained using both standard generalized gradient corrected and hybrid functionals, are compared with previous published theoretical data and the available experimental findings. It is,shown that hybrid functionals give results close to highly correlated post Hartree-Fock approaches and which are sensibly different from those obtained by standard local, even gradient corrected, methods. A nice agreement has been also found between theoretical and experimental binding energies. A natural bond orbital analysis confirms the role of the pi interaction in the metal-carbonyl bond and gives an explanation to the preference for bent structures found in chromium and copper monocarbonyls. (C) 1995 Amerian Institute of Physics.