DVM -Xα Study of Anomalous Magnetic Property in Co₆Te₈ Cluster

The anomalous megnetic property of neutral Co₆Te₈ cluster is investigated by DVM-X_a calculation of molecular orbitals. For the structure with O_h symmetry, the DVM-X_a results shows that the electronic configuration of ground state is non magnetic, and is disagreement with experimental data. However,if the John-Teller effect due to non spherical charge distribution of partially filled 3d levels of transition metal is involved, i. e., the D_4h symmentry is adopted for Co₆Te₈ cluster the mixed-valence-like electronic configuration is obtained. The ground state with John-Teller distortion is non magnetic with double-occupied HOMO,and the LUMO is low-lying and the gap between HOMO and LUMO is about 0. 018eV. These results explain qualitatively the experimental data well and are in good agreement with mixed-valence model of heavy fermion system.