Bonding in the Mg4 cluster. An example of chemical bonding originating from electron correlation effects

Abstract

The Mo4 cluster has been examined with SCF and correlated SCEP and CEPA-2 treatments. It is found that little or no binding is obtained when either correlation effects of atomic 3d functions in the basis set are excluded. However, calculations including correlation effects and utilizing a basis set containing d functions demonstrated chemical bonding and yield A cluster formation energy of about 20 kcal/mole.