Electronic structure and chemical bonding in metallic clusters of binary and ternary transition metal chalcogenides. I. SCF MS X α study including relativistic effect of PbMo6S8

Cluster calculations of the electronic structure and charge distribution of PbMo6S8 have been performed using the SCF Xα scattered-wave method. These results compare fairly well with those obtained with solid state methods and ionization energies are in agreement with XPS experimental spectra. Moreover, the chemical bonding, particulary the interactions between the Mo6 metallic clusters with its chalcogenide neighboring, is discussed by comparing the results obtained for the Mo6 and (Mo6S8)2− units. These main features are also illustrated by using both the partial wave population analysis and contour map of some bonding molecular orbitals of the valence band. The importance of relativistic effects on such metal 4d compounds is discussed.