Nature of Mo-Mo and Cr-Cr multiple bonds: a challenge for the local-density approximation.

Abstract

The full potential curves for ${\mathrm{Mo}}_{2}$ (and ${\mathrm{Cr}}_{2}$) have been examined by using highly correlated wave functions. A competition is found between $5s\ensuremath{-}5s$ bonding and $4d\ensuremath{-}4d$ bonding, so that the lower states lead to two minima, with the inner minimum involving $d\ensuremath{\sigma}$, $d\ensuremath{\pi}$, and $d\ensuremath{\delta}$ bonds. The results disagree dramatically with those from local-density calculations, and the present analysis suggests that this approximation (in its current formulation) is unsuitable for describing multiple bonds in transition-metal systems.

Group Members

William A. Goddard III

Charles and Mary Ferkel Professor