Magnetic properties of Cr2On− clusters: A theoretical study

The chromium ions in each of the chromium oxide cluster anions Cr2O−, Cr2O2− and Cr2O3− have been found to be ferro-magnetically coupled to each other. In each case, one of the highest spin states is the ground state. In fact, the ground states correspond to the spin multiplicities 10, 10 and 8, respectively. The magnetic interaction proceeds via super exchange mechanism. The intra-molecular ferromagnetic exchange coupling constant is estimated from the density functional methodology using broken symmetry approach. It is found to decrease steadily with increasing number of oxygen atoms. A rationale for this phenomenon can be given from molecular orbital analysis.