The A2Î u state of N2+: Electric properties, fine and hyperfine coupling constants, and magnetic moments (g-factors). A theoretical study

Several properties are calculated for A2Πu of N2+-the majority for the first time-including electric and magnetic moments, and fine/hyperfine structure (fs/hfs) parameters. The new results are compared with our previous ones for X2Σg+ and B2Σu+ of N2+ [P.J. Bruna, F. Grein, J. Mol. Spectrosc. 227 (2004) 67-80]. The electric quadrupole Θ and hexadecapole Φ moments, polarizability α, and hfs constants a, b, c, d, eQq0, eQq2 are evaluated at the density functional theory (DFT) level [B3LYP/aug-cc-pVQZ]. The fs constants (spin-orbit coupling AΠ, Λ-doubling p, q, spin-rotation γΠ), and magnetic moments (g-factors) are obtained via 2nd-order sum-over-states expansions, using wavefunctions and matrix elements obtained with a multireference configuration interaction (MRDCI) method, and the Breit-Pauli Hamiltonian. At equilibrium, 2nd-order properties of A2Πu are dominated by its coupling with B2Σu+. For the A state, two independent components are reported for traceless tensor properties (multipoles Θ and Φ; hfs parameters c/d and q0/q2) and three for traced properties (polarizability α and g-factors), i.e., one more component than for axially symmetric Σ states. The currently available experimental data on A2Πu(N2+)- limited to AΠ, p, and q-are well reproduced by our theoretical results.