Potential energy curves and electronic structure of copper nitrides CuN and CuN+ versus CuO and CuO+

Ab initio configuration interaction calculations for the diatomic CuO, CuN, CuO+, and CuN+ have been carried out, and potential energy curves are repo rted for several low-lying states of these systems. The electronic structur e and bonding, not yet known for the neutral copper nitride and its cation, are examined and compared to those of the copper oxide systems. We find th at the ground states of these systems are X(2)Pi (CuO), X(3)Sigma(-) (CuN), X(3)Sigma(-) (CuO+), and X(4)Sigma(-) (CuN+); their first low-lying excite d states Y(2)Sigma(+), (1)Delta, (1)Delta, and (2)Pi are located at 0.69, 1 .45, 2.32, and 2.09 eV, respectively. For CuO we found two unobserved quart er states, namely (4)Sigma(-) (T-e = 1.09 eV) and (4)Pi (T-e = 1.86 eV). We report equilibrium structural parameters for various electronic states of the studied systems and compare them with experimental values, where it is possible, (C) 1999 Academic Press.