Accurate potential energy curves and spectroscopic properties of the 27 Λ-S states and 73 Ω states of the PO radical

Abstract

ABSTRACTThe potential energy curves (PECs) were calculated for the 27 Λ-S states and 73 Ω states of PO radical. The calculations were done using the CASSCF method, which was followed by the internally contracted multireference configuration interaction (icMRCI) approach. To improve the quality of PECs, core-valence correlation and scalar relativistic corrections as well as Davidson correction were included. Of the 27 Λ-S states, the 16Σ+ state was repulsive at any case. The 14Φ and 16Π states were bound, but they became repulsive with the spin-orbit coupling (SOC) effect accounted for. The 34Σ+, a4Π, C′2Δ, D′2Π, 14Δ, 12Φ, 16Σ+ and 16Π states were inverted with the SOC effect included. The F2Σ+ state had double wells. The avoided crossings existed between the B2Σ+ and F2Σ+ states, the F2Σ+ and 32Σ+ states, the C′2Δ and 22Δ states, the 14Δ and 24Δ states, the 24Δ and 34Δ states, the 24Π and 34Π states and the 34Π and 44Π states. The c4Σ+, 24Σ+, 34Σ+, 34Π, 44Π, 54Π, 34Δ, 14Φ and 16Π states were weakly bound, which well depths were within several hundred cm−1. The spectroscopic parameters were derived. The SOC effect on the spectroscopic properties was evaluated. The spectroscopic results obtained here could be expected to be reliably predicted ones.