15min:

TSUNEO HIRANO AND UMPEI NAGASHIMA, Grid Technology Research Center, Institute of Advanced Industrial Science and Technology, 6-9-3 Ueno, Taito-ku, Tokyo 110-0015, Japan.

Based on the information from Tanaka group of Hokkaido University, we have studied the ^{1 +} and ⁵ states of CoN by ab initio molecular orbital methods as an extension of our previous work on FeN. The MR-SDCI+Q+ E_rel/[Roos ANO(Co), aug-cc-pVQZ(N)] calculations with full-valence plus Co 3s and 3p electron correlations predicted that the ⁵ level should be located by about 4300 cm^{- 1} higher than the ^{1 +} state. Hence, the electronic ground state is ^{1 +} . The equilibrium bond lengths for the ^{1 +} and ⁵ states at this level of calculation are 1.5621 and 1.5945 Å, respectively. The first order relativistic correction E_rel increases linearly with the Co-N bond length, with steeper gradient for ^{1 +} than ⁵ states as is expected. The resultant shortening of the Co-N bond due to the relativistic effect is 0.016 and 0.005 Å for the ^{1 +} and ⁵ states, respectively.