CALCULATION OF THE LOW-SPIN AND HIGH-SPIN STATES OF I(H) CO13

We have studied the electric structure of an icosahedral (I(h)) 13-atom cobalt (Co13) cluster, which is the smallest cluster in the icosahedral structure, using the discrete variational Xalpha cluster method. We have found that two electric states in the I(h) Co13 cluster-a low-spin state and a high-spin state-exist with the interatomic distance of equilibrium geometry. The average magnetic moment of the low-spin state of the cluster is 1. 77mu(B), while that of the high-spin state is 2.23mu(B). It seems that the magnetic moments extrapolating these results are in agreement with the magnetic doublets of the Co55 cluster Bucher et al. observed. The magnetic doublets of the Co55 cluster may be due to those of the I(h) Co55 cluster.