Spectroscopic Constants and Predissociation of the low-lying states in selenium dimer

High-level ab initio calculations on the electronic structure and spectroscopic properties for the low-lying electronic states of selenium dimer (Se2) are performed by using internally contracted multireference-configuration interaction method (icMRCI) including Davidson correction ( + Q ) and scalar relativistic effect (SR). The spin-orbit coupling (SOC) effect is introduced in the computations via state-interacting technique with the full Breit-Pauli Hamiltonian. The potential energy curves (PECs) of 22 A-S states of Se2 are com-puted. After taking SOC effect into account, PECs of 28 Q states generated from the A-S states with the energy under 36,0 0 0cm -1 are yielded. Moreover, from the calculated PECs, the spectroscopic constants of the bound A-S and Q states are determined, and good agreement with available experimental and theoretical works is found. By virtue of the calculated SOC matrix elements and the PECs of the A-S states, the spin-orbit induced predissociation mechanism of the B3Eu- state is discussed. Our computa-tions would provide helpful information on spectroscopic properties of the low-lying electronic states for the Se2, and deep understanding of the predissociation mechanism for the B3Eu- state.(c) 2023 Elsevier Ltd. All rights reserved.

Automated summary

High-level ab initio calculations are performed on the electronic structure and spectroscopic properties of Se2 using icMRCI method with Davidson correction and SR effect. The SOC effect is considered via state-interacting technique with the full Breit-Pauli Hamiltonian. The PECs of 22 A-S states of Se2 are computed, and after taking SOC effect into account, PECs of 28 Q states are obtained. The spectroscopic constants of the bound A-S and Q states are determined, and the spin-orbit induced predissociation mechanism of the B3Eu- state is discussed.