MRCI study of the spectroscopic parameters and transition properties of the 36 low-lying electronic states of the B2 molecule

作者：Xing, Wei; Shi, Deheng^*; Sun, Jinfeng; Zhu, Zunlue

来源：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy , 2017, 185: 349-364.

DOI：10.1016/j.saa.2017.05.074

• Potential energy curve
• Spectroscopic parameter
• Transition dipole moment
• Electric dipole transition
• Avoided crossing
• Vibrational state

This paper studied the spectroscopic and transition properties of 36 low-lying states, which came from the first two dissociation limits of B-2 molecule. The potential energy curves were calculated with the complete active space self-consistent field (CASSCF) method, which was followed by the internally contracted multireference configuration interaction (icMRCI) plus Davidson modification (icMRCI + Q) approach. Of these 36 states, the 2(5)Sigma(-)(u), 5 Sigma(+)(u), 2(5)Pi(u), and 1(5)Delta(u), states were repulsive; the B-3 Delta(u), E-3 Sigma(+)(u), 2(3)Pi(u), 3(3)Sigma(-)(g), 3(3)Sigma(-)(g) 1(5)Pi(g), and 3(3)Sigma(+)(u) states had double wells; the B-3 Delta(u), E-3 Sigma(+)(u), G(3)Sigma(+)(u), f(1)Sigma(-)(u), 3(3)Sigma(-)(g), 2(3)Pi(u), E-3 Sigma(+)(u), 2(3)Pi(u), 3(3)Sigma(-)(g), 3(3)Sigma(-)(g) 1(5)Pi(g) and 3(3)Delta(u) states had one barrier; the 2(5)Sigma(+)(g) state and the second wells of 3(3)Sigma(-)(g), 3(3)Sigma(-)(g), and 3(3)Sigma(-)(g) states were weakly bound; and the 3(3)Sigma(-)(g) state had no vibrational levels. The avoided crossings existed between the B-3 Delta(u) and 2(3)Delta(u) states, the E-3 Sigma(+)(u) and G(3)Sigma(+)(u), states, the G(3)Sigma(+)(u) and 3(3)Sigma(+)(u) states, the 3(3)Sigma(+)(u) and 4(3)Sigma(+)(u) states, the 2(3)Pi(u) and 3(3)Pi(u) states, the g(1)Pi(g) and 2(1)Pi(g) states, the 2(3)Sigma(-)(g) and 3(3)Sigma(-)(g) states, the 1(5)Pi(g) and 2(5)Pi(g) states, the 2(5)Pi(g) and 3(5)Pi(g) states, the 2(5)Sigma(-)(g) and 3(5)Sigma(-)(g) states, as well as the F-3 Pi(g) and 3(3)Pi(g) 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 obtained. The transition dipole moments were calculated. Franck-Condon factors of some transitions were evaluated. The spin-orbit coupling (SOC) effect on the spectroscopic parameters and vibrational properties is tiny and sometimes even can be negligible. The results determined in this paper can provide some powerful guidelines to observe these states, in particular the states which have not been studied in the experiment.

• 出版日期2017-10-5
• 单位河南师范大学; 信阳师范学院