Renner–Teller interactions coupled to large spin–orbit splittings: The BrCN+ case

A theoretical study of spin-rovibronic levels arising from Renner–Teller and spin–orbit couplings in the ground X2Π state of BrCN+ is reported. Vibronic energy levels of Σ, Π, Δ, Φ symmetry, up to ≈9000 cm−1 have been calculated variationally, using highly accurate ab initio full-dimensional potential energy surfaces and taking explicitly into account the geometry dependence of the spin–orbit coupling. Results are compared to available experimental data.