Ab-initio calculations of the electronic structure of the alkaline earth hydride anions XH− (X = Mg, Ca, Sr and Ba) toward laser cooling experiment

Zeid, Israa; Abdallah, Rania Al; El-Kork, Nayla; Korek, Mahmoud

doi:10.1016/j.saa.2019.117461

Cited by 13 publications

(7 citation statements)

References 35 publications

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“…The C 2v symmetry is used for the constrained PEC scanning, while the C s symmetry is used for the un-constrained PEC scanning. The selection of active space is very important for the icMRCI + Q calculations (Yu and Bian, 2012;Feller et al, 2014;El-Kork et al, 2017;Zeid et al, 2020;Li and Bian, 2021;Moussa et al, 2021). Here, the chosen active space includes 7 electrons in 13 orbitals for CaNC or SrNC.…”

Section: Methods and Computational Detailmentioning

confidence: 99%

Production of ultracold polyatomic molecules with strong polarity by laser cooling: A detailed theoretical study on CaNC and SrNC

Xia

Cao

et al. 2022

Front. Chem.

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Laser cooling molecules to the ultracold regime is the prerequisite for many novel science and technologies. It is desirable to take advantage of theoretical approaches to explore polyatomic molecular candidates, which are capable of being cooled to the ultracold regime. In this work, we explore two polyatomic candidates, CaNC and SrNC, which are suitable for laser cooling. These molecules possess impressively large permanent dipole moments (∼6 Debye), which is preferred for applications using an external electric field. High-level ab initio calculations are carried out to reveal electronic structures of these molecules, and the calculated spectroscopic constants agree very well with the available experimental data. For each molecule, the Franck-Condon factor matrix is calculated and shows a diagonal distribution. The radiative lifetimes for CaNC and SrNC are estimated to be 15.5 and 15.8 ns, respectively. Based upon the features of various electronic states and by choosing suitable spin-orbit states, we construct two feasible laser cooling schemes for the two molecules, each of which allows scattering nearly 10000 photons for direct laser cooling. These indicate that CaNC and SrNC are excellent ultracold polyatomic candidates with strong polarity.

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Section: Methods and Computational Detailmentioning

confidence: 99%

Production of ultracold polyatomic molecules with strong polarity by laser cooling: A detailed theoretical study on CaNC and SrNC

Xia

Cao

et al. 2022

Front. Chem.

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“…The potential energy curves and dipole moment curves of the ground and excited electronic states were investigated for the molecules BeSe and BeTe, respectively. The calculations were performed by employing the MCSCF/MRCI technique, similar to our previously published work. − The current study was performed at the spin-free and spin-orbit coupling level. The spectroscopic constants T e , R e , ω e , and B e and the dissociation energy D e have been calculated for most of the bound states.…”

Section: Discussionmentioning

confidence: 99%

Electronic Structures and Transition Properties of BeSe and BeTe Molecules

et al. 2021

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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 T e, R e, ωe, and B e, and the dissociation energy D e 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 E v, B v, and D v and the turning points R min and R max. 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.

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“…For this molecule, the 15 active orbitals in the C 2 v symmetry are 8σ (Ca: 4s, 4p 0 , 3d 0 , 3d ± 2, 5s; Na: 3s, 3p 0 , 4s), 3π (Ca: 4p ± 1, 3d ± 1; Na: 3p ± 1), 1δ (Ca: 3d ± 2) distributed into the irreducible representation a 1, b 1, b 2, and a 2 as [8, 3, 3, 1]. We used this combination of basis sets for the two molecules due to the successful results obtained by other groups and previously published papers 32 − 35 that used a similar combination of basis sets for AK–AKE compounds. Additionally, and for more accuracy and comparison, we used the perturbation theory (Rayleigh–Schrödinger perturbation theory) RSPT2-rs2 to calculate the spectroscopic constants for some electronic states for CaCs and CaNa molecules.…”

Section: Computational Approachmentioning

confidence: 99%

Laser Cooling with an Intermediate State and Electronic Structure Studies of the Molecules CaCs and CaNa

et al. 2022

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The ground and excited electronic states of the diatomic molecules CaCs and CaNa have been investigated by implementing the ab initio CASSCF/(MRCI + Q) calculation. The potential energy curves of the doublet and quartet electronic low energy states in the representation 2 s +1 Λ (±) have been determined for the two considered molecules, in addition to the spectroscopic constants T e , ω e , B e , R e , and the values of the dipole moment μ e and the dissociation energy D e . The determination of vibrational constants E v , B v , D v , and the turning points R min and R max up to the vibrational level v = 100 was possible with the use of the canonical functions schemes. Additionally, the transition and the static dipole moments curves, Einstein coefficients, the spontaneous radiative lifetime, the emission oscillator strength, and the Franck–Condon factors are computed. These calculations showed that the molecule CaCs is a good candidate for Doppler laser cooling with an intermediate state. A “four laser” cooling scheme is presented, along with the values of Doppler limit temperature T D = 55.9 μK and the recoil temperature T r = 132 nK. These results should provide a good reference for experimental spectroscopic and ultra-cold molecular physics studies.

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Ab-initio calculations of the electronic structure of the alkaline earth hydride anions XH− (X = Mg, Ca, Sr and Ba) toward laser cooling experiment

Cited by 13 publications

References 35 publications

Production of ultracold polyatomic molecules with strong polarity by laser cooling: A detailed theoretical study on CaNC and SrNC

Production of ultracold polyatomic molecules with strong polarity by laser cooling: A detailed theoretical study on CaNC and SrNC

Electronic Structures and Transition Properties of BeSe and BeTe Molecules

Laser Cooling with an Intermediate State and Electronic Structure Studies of the Molecules CaCs and CaNa

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Ab-initio calculations of the electronic structure of the alkaline earth hydride anions XH− (X = Mg, Ca, Sr and Ba) toward laser cooling experiment

Cited by 13 publications

References 35 publications

Production of ultracold polyatomic molecules with strong polarity by laser cooling: A detailed theoretical study on CaNC and SrNC

Production of ultracold polyatomic molecules with strong polarity by laser cooling: A detailed theoretical study on CaNC and SrNC

Electronic Structures and Transition Properties of BeSe and BeTe Molecules

Laser Cooling with an Intermediate State and Electronic Structure Studies of the Molecules CaCs and CaNa

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Product

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Ab-initio calculations of the electronic structure of the alkaline earth hydride anions XH− (X = Mg, Ca, Sr and Ba) toward laser cooling experiment