Electronic Structures and Transition Properties of BeSe and BeTe Molecules.

Israa Zeid,Hela Ladjimi,Nayla El-Kork,Mohamed Farjallah,Hamid Berriche,Mahmoud Korek

doi:10.1021/acsomega.1c03170

Israa Zeid, Hela Ladjimi + Show 4 more

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https://doi.org/10.1021/acsomega.1c03170

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Abstract

The electronic structure of BeSe and BeTe molecules has been investigated using the ab initio CASSCF/(MRCI + Q) method at the spin-free and spin-orbit level. The potential energy curves, the permanent dipole moment, the spectroscopic constants Te, Re, ωe, and Be, and the dissociation energy De are determined in addition to the vertical transition energy Tv. The molecules’ percentages of ionic character are deduced, and the trends of the spectroscopic constants of the two molecules are compared and justified. A ro-vibrational study is performed using the canonical function approach to calculate the constants Ev, Bv, and Dv and the turning points Rmin and Rmax. All the ground-state vibrational levels have also been investigated. The radiative lifetimes of vibrational transitions among the electronic ground states are also discussed. The results for BeSe have been compared with the previously published data while those for BeTe molecules are presented here for the first time.

Highlights

Solid-state beryllium chalcogenides (BeS, BeSe, and BeTe) exhibit several interesting physical properties related to their electronic structure; they present high bonding energy, hardness, and unusual electronic, mechanical, thermal, and optical properties
The BeSe molecule has been the subject of the study conducted by Larbi et al in 2021 where it is investigated via MRCI + Q in singlet, triplet, and quintet multiplicities.[15]
The potential energy and the dipole moment curves for the singlet and triplet states calculated using the ECPMWB basis set for Se and Te are given in Figures 1−4 while those related to the quintet states are given in figures (FS1−FS4) in the Supporting Information

Summary

INTRODUCTION

Solid-state beryllium chalcogenides (BeS, BeSe, and BeTe) exhibit several interesting physical properties related to their electronic structure; they present high bonding energy, hardness, and unusual electronic, mechanical, thermal, and optical properties. The molecule BeS has been studied experimentally and theoretically in the gaseous state.[11,12] Its electronic properties have been found to be very helpful in the advancement of attosecond physics and the exploration of the dynamical motion of electrons.[13,14] the BeSe molecule has been the subject of the study conducted by Larbi et al in 2021 where it is investigated via MRCI + Q in singlet, triplet, and quintet multiplicities.[15] The molecule BeTe, on the other hand, has not been studied either experimentally or theoretically yet. The active space in the C2v symmetry group contains 5σ (Be: 2s, 2p0, 3s, and 3p0 and Se: 4p0), 2π (Be:2p ± 1 and Se: 4p ± 1), and 0δ (Be:[0] and Se:0) and 7σ (Be: 2s, 2p0, 3s,3p0, 3d0, and 3d + 2 and Te: 5p0), 4π (Be:2p ± 1,3p ± 1, and 3d + 1 and Te: 5p ± 1), and 1δ (Be:3d − 2 and Te:0) orbitals distributed into the irreducible representation as 5a1, 2b1, 2b2, and 0a2 and 7a1, 4b1, 4b2, and 1a2, which correspond to [5,2,2,0] and [7,4,1,1] for the molecules BeSe and BeTe, respectively

COMPUTATIONAL APPROACH

RESULTS AND DISCUSSION

CONCLUSIONS

■ REFERENCES