Force field calculations for nearest neighbor transition metal ion pairs in cubic ZnS

Abstract

Force field calculations for the totally symmetric a 1 vibrations of nearest neighbor transitionmetal (TM) ion pairs in cubic ZnS ( M 2 S 7 10−, M = Mn, Fe, Co, Ni) have been performed by the INDO/2 method. The calculated force constants are considerably lower compared to those obtained for isolated MS 4 6− clusters. This finding is explained by the presence of M-M bonding and charge transfer from the bridging S atom to the metal ions. The trends in the force constants and equilibrium M-S distances are explained in terms of the bonding parameters for TM ion doped II–VI compounds previously reported.