Knowledge Bank

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