Multireference configuration interaction study of the 27 low-lying states of the PF⁺ cation

This paper studied the spectroscopic parameters and vibrational properties of 27 Λ-S and 60Ω states of PF⁺ cation. The 27 Λ-S states were the X²Π, A²Σ⁺, B²Π, C²Σ^-, D²Δ, a⁴Σ^-, b⁴Π, c⁴Σ⁺, d⁴Δ, 2²Σ⁺, 3²Σ⁺, 4²Σ⁺, 2²Σ^-, 3²Σ^-, 3²Π, 4²Π, 5²Π, 6²Π, 2²Δ, 3²Δ, 1²Φ, 2⁴Σ^-, 3⁴Σ^-, 2⁴Π, 3⁴Π, 1⁶Σ^-, and 1⁶Π, which were generated from the first four dissociation limits. The 60Ω states were produced from the 27 Λ-S states. All the potential energy curves were calculated with the CASSCF method, which was followed by the icMRCI+Q approach. The a⁴Σ^-, b⁴Π, and D²Δ states were inverted with the spin-orbit coupling effect accounted for. The 2⁴Π, 2⁴Σ^-, 2²Δ, 3²Δ, 3²Σ⁺, 4²Σ⁺, 1²Φ, and 2²Σ^- states were repulsive whether the spin-orbit coupling effect was included or not, but the 5²Π and D²Δ states became repulsive only with the spin-orbit coupling effect included. The C²Σ^- state was very weakly bound. The a⁴Σ^- state had one barrier. The avoided crossings existed between the a⁴Σ^- and 2⁴Σ^- states, the 2²Σ⁺ and 3²Σ⁺ states as well as the D²Δ and 2²Δ states. Core-valence correlation and scalar relativistic corrections were taken into account. The extrapolation to the complete basis set limit was done. The spectroscopic parameters and vibrational properties were determined. The transition dipole moments were calculated and the Franck-Condon factors of some electric dipole transitions were evaluated. The spin-orbit coupling effect on the spectroscopic and vibrational properties was discussed.