MRCI study on the spectroscopic parameters, transition dipole moments and transition probabilities of 16 low-lying states of the BeB radical. (March 2018)

• Record Type: Journal Article
• Authors: Zhou, Dan; Shi, Deheng; Sun, Jinfeng; Zhu, Zunlue
• Is Part Of: Journal of quantitative spectroscopy & radiative transfer. Volume 208(2018)
• Page Start: 1
• Page End: 11
• Publication Date: 2018-03
• Subjects: Potential energy curve -- Spectroscopic parameter -- Electric dipole transition -- Spin-orbit coupling -- Transition probability -- Franck–Condon factor; Spectrum analysis -- Periodicals; Radiation -- Periodicals; Analyse spectrale -- Périodiques; Rayonnement -- Périodiques; Radiation; Spectrum analysis; Periodicals; 543.0858
• DOI: 10.1016/j.jqsrt.2017.12.024
• Languages: English
• ISSNs: 0022-4073

Abstract

Highlights: PECs are extrapolated to the CBS limit. Transition properties including the FC factors are calculated. Spectroscopic and vibrational properties are determined for all the states. SOC effect on the spectroscopic and vibrational properties is discussed. Only the d 4 Δ, e 4 Σ +, and g 4 Π states and the second well of h 4 Π state are very weakly bound. Abstract: In this work, we calculate the potential energy curves of 16 Λ-S and 36 Ω states of beryllium boride (BeB) radical using the complete active space self-consistent field method, followed by the valence internally contracted multireference configuration interaction approach with Davidson correction. The 16 Λ-S states are the X 2 Π, A 2 Σ +, B 2 Π, C 2 Δ, D 2 Ʃ −, E 2 Σ +, G 2 Π, I 2 Σ +, a 4 Σ −, b 4 Π, c 4 Σ −, d 4 Δ, e 4 Σ +, g 4 Π, h 4 Π, and 2 4 Σ +, which are obtained from the first three dissociation channels of the BeB radical. The Ω states are obtained from the Λ-S states. Of the Λ-S states, the G 2 Π, I 2 Σ +, and h 4 Π states exhibit double well curves. The G 2 Π, b 4 Π, and g 4 Π states are inverted with the spin-orbit coupling effect included. The d 4 Δ, e 4 Σ +, and g 4 Π states as well as the second well of the h 4 Π state are very weakly bound. Avoided crossings exist between the G 2 Π and H 2 Π states, the A 2 Σ + and E 2 Σ + states, the c 4 Σ − and f 4 Σ − states, the g 4 Π and h 4 Π states, the I 2 Σ + and 4 2 Σ + states, as well as the 2 4 Σ + and 3 4 Σ + states. To improve the quality of the potential energy curves, core-valence correlation and scalar relativistic corrections, as well as the extrapolation of the potential energies to the complete basis set limit, are included. The transition dipole moments are computed. Spectroscopic parameters and vibrational levels are determined along with Franck–Condon factors, Einstein coefficients, and radiative lifetimes of many electronic transitions. The transition probabilities are evaluated. The spin-orbit coupling effect on the spectroscopic parameters and vibrational levels is discussed. The spectroscopic parameters, vibrational levels, and transition probabilities reported in this paper can be considered very reliable and can be employed to predict these states in an appropriate spectroscopy experiment. Graphical abstract: This paper calculates the potential energy curves, spectroscopic parameters, transition dipole moments, and transition probabilities of the BeB radical. Overall, the X 2 Π, A 2 Σ +, B 2 Π, C 2 Δ, D 2 Ʃ −, E 2 Σ +, I 2 Σ +, a 4 Σ −, b 4 Π, c 4 Σ −, and 2 4 Σ + states can be detected spectroscopically according to the routines proposed in this paper. The g 4 Π state, the first well of the G 2 Π state, and the second well of the h 4 Π state are very difficult to observe because almost all the transitions arising from them are very weak. The d 4 Δ and e 4 Σ + states as well as the first well of h 4 Π state are very weakly bound, requirng great efforts to explore them spectroscopically.