The increase of the number of the two-body recombination channels strongly challenges the numeric... more The increase of the number of the two-body recombination channels strongly challenges the numerical calculation of the accurate rates for the three-body recombination (TBR) process and its reverse process, collision-induced dissociation (CID), at ultracold temperatures. By taking the 4He–4He–20Ne collision system as an example, we have obtained the rates for its TBR and CID processes involving all four recombination channels, including the two-body states 4He2 ( l = 0) and 4He20Ne ( l = 0, 1, 2) with l the rotational quantum number. By using the adiabatic hyperspherical method, we have considered not only total angular momentum J = 0 but also J > 0 in the ultracold collision energies ( E = 0.01 − 100 mK × kB). It is found that 4He2 ( l = 0) is the major product after the TBR process in the ultracold limit ( E ≤ 0.1 mK × kB). The TBR rate into 4He2 ( l = 0) is nearly one order of magnitude larger than the sum of the other three products, 4He20Ne ( l = 0, 1, 2). Moreover, the CID r...
By solving the full-dimensional time-dependent Schrödinger equation with the thermal-random-phase... more By solving the full-dimensional time-dependent Schrödinger equation with the thermal-random-phase wavepacket method, we investigate the photoassociation (PA) process of hot (1000 K) magnesium atoms induced by two time-delayed femtosecond laser pulses. Driven by the 840 nm fs laser pulses, the Mg2 molecules can be formed on the four excited states, (1)1Πg, (1)1Πu, (2)1Πu, and (2)1Σu+, from the initial electronic ground state X1Σg+. It is found that the three-photon couplings between X1Σg+ and the three ungerade states [(1)1Πu (2)1Πu, and (2)1Σu+], play dominant roles in the population transfer process. By scanning the pulse duration τ from 50 to 200 fs, and varying the delay time δt0 from 0 to 2τ fs, we find that the final PA population is strongly dependent on the two parameters. For a given δt0, the parameter τ can induce a significant variation (2 ∼ 6.8 times) for the final PA population transfer, and for a given τ, one can also obtain a significant variation (2.7 ∼ 3.5 times) of ...
The effect of collision energy on the magnetically tuned 6Li-6Li Feshbach resonance (FR) is inves... more The effect of collision energy on the magnetically tuned 6Li-6Li Feshbach resonance (FR) is investigated theoretically by using the coupled-channel (CC) method for the collision energy ranging from 1 to 100 (μK · kB). At the collision energy of 1 μK · kB, the resonance positions calculated are 543.152 G (s wave), 185.109 G (p wave |m l | = 0) and 185.113 G (p wave |m l | = 1), respectively. The p-wave FR near 185 G exibits a doublet structure of 4 mG, associated with dipole-dipole interaction. With the increase of the collision energy, it is found that the splitting width remains the same (4 mG), and that the resonance positions of s and p waves are shifted to higher magnetic fields with the increase of collision energy. The variation of the other quantities include the resonance width and the amplitude of the total scattering section are also discussed in detail. The thermally averaged elastic rate coefficients at T = 10, 15, 20, 25 K are calculated and compared.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2022
The potential energy curves of the ground and five low-lying excited terms of the RaF molecule ar... more The potential energy curves of the ground and five low-lying excited terms of the RaF molecule are calculated using the Fock-space relativistic coupled theory. The electronic term energies, equilibrium internuclear distances, transition and permanent dipole moments, sequences of vibrational energies, harmonic vibrational frequencies, Franck-Condon factors, and radiative lifetimes are predicted. The calculated spectroscopic constants are in good agreement with the available theoretical and experimental data. The scheme for the direct laser cooling involving the first excited A2П1/2 state is proposed. The data obtained in this study suggests the A2П1/2 → X2Σ+ channel in the RaF molecule is the almost ideal case for direct laser cooling. It is quite possible that the effective cooling scheme for the RaF molecule can be realized using only one pump laser.
Abstract The potential energy curves of the ground and eight low-lying excited atomic and ionic t... more Abstract The potential energy curves of the ground and eight low-lying excited atomic and ionic terms of the RaCl molecule are calculated for the first time using the multi-reference perturbation theory method at the CASSCF/XMCQDPT2 level of theory including the spin-orbit coupling. The electronic term energies, equilibrium internuclear distances, dissociation energies, transition dipole moments, sequences of vibrational energies, harmonic vibrational frequencies, Franck–Condon factors, and radiative lifetimes are predicted. The data obtained in this study suggests the possibility of the direct laser cooling of the RaCl molecules.
Journal of Quantitative Spectroscopy and Radiative Transfer, 2021
Abstract The potential energy curves of the ground and five low-lying excited states of the RaBr ... more Abstract The potential energy curves of the ground and five low-lying excited states of the RaBr molecule are calculated using the Fock-space relativistic coupled cluster theory for the first time. A number of properties such as the electronic term energies, equilibrium internuclear distances, transition and permanent dipole moments, sequences of vibrational energies, harmonic vibrational frequencies, Franck–Condon factors, and radiative lifetimes are predicted. The results of this study show that RaBr molecules can be used for the direct laser cooling. The comparison to the previous theoretical studies of the RaF and RaCl molecules is also provided.
Based on a high level ab initio calculation which is carried out with the multireference configur... more Based on a high level ab initio calculation which is carried out with the multireference configuration interaction method under the aug-cc-pVXZ (AVXZ) basis sets, X = T, Q, 5, the accurate potential energy curves (PECs) of the ground state X Σ g + 1 and the first excited state A Σ u + 1 of Li2 are constructed. By fitting the ab initio potential energy points with the Murrell–Sorbie potential function, the analytic potential energy functions (APEFs) are obtained. The molecular bond length at the equilibrium (R e ), the potential well depth (D e ), and the spectroscopic constants (B e , ω e , α e , and ω e χ e ) for the X Σ g + 1 state and the A Σ u + 1 state are deduced from the APEFs. The vibrational energy levels of the two electronic states are obtained by solving the time-independent Schrödinger equation with the Fourier grid Hamiltonian method. All the spectroscopic constants and the vibrational levels agree well with the experimental results. The Franck–Condon factors (FCFs) co...
The increase of the number of the two-body recombination channels strongly challenges the numeric... more The increase of the number of the two-body recombination channels strongly challenges the numerical calculation of the accurate rates for the three-body recombination (TBR) process and its reverse process, collision-induced dissociation (CID), at ultracold temperatures. By taking the 4He–4He–20Ne collision system as an example, we have obtained the rates for its TBR and CID processes involving all four recombination channels, including the two-body states 4He2 ( l = 0) and 4He20Ne ( l = 0, 1, 2) with l the rotational quantum number. By using the adiabatic hyperspherical method, we have considered not only total angular momentum J = 0 but also J > 0 in the ultracold collision energies ( E = 0.01 − 100 mK × kB). It is found that 4He2 ( l = 0) is the major product after the TBR process in the ultracold limit ( E ≤ 0.1 mK × kB). The TBR rate into 4He2 ( l = 0) is nearly one order of magnitude larger than the sum of the other three products, 4He20Ne ( l = 0, 1, 2). Moreover, the CID r...
By solving the full-dimensional time-dependent Schrödinger equation with the thermal-random-phase... more By solving the full-dimensional time-dependent Schrödinger equation with the thermal-random-phase wavepacket method, we investigate the photoassociation (PA) process of hot (1000 K) magnesium atoms induced by two time-delayed femtosecond laser pulses. Driven by the 840 nm fs laser pulses, the Mg2 molecules can be formed on the four excited states, (1)1Πg, (1)1Πu, (2)1Πu, and (2)1Σu+, from the initial electronic ground state X1Σg+. It is found that the three-photon couplings between X1Σg+ and the three ungerade states [(1)1Πu (2)1Πu, and (2)1Σu+], play dominant roles in the population transfer process. By scanning the pulse duration τ from 50 to 200 fs, and varying the delay time δt0 from 0 to 2τ fs, we find that the final PA population is strongly dependent on the two parameters. For a given δt0, the parameter τ can induce a significant variation (2 ∼ 6.8 times) for the final PA population transfer, and for a given τ, one can also obtain a significant variation (2.7 ∼ 3.5 times) of ...
The effect of collision energy on the magnetically tuned 6Li-6Li Feshbach resonance (FR) is inves... more The effect of collision energy on the magnetically tuned 6Li-6Li Feshbach resonance (FR) is investigated theoretically by using the coupled-channel (CC) method for the collision energy ranging from 1 to 100 (μK · kB). At the collision energy of 1 μK · kB, the resonance positions calculated are 543.152 G (s wave), 185.109 G (p wave |m l | = 0) and 185.113 G (p wave |m l | = 1), respectively. The p-wave FR near 185 G exibits a doublet structure of 4 mG, associated with dipole-dipole interaction. With the increase of the collision energy, it is found that the splitting width remains the same (4 mG), and that the resonance positions of s and p waves are shifted to higher magnetic fields with the increase of collision energy. The variation of the other quantities include the resonance width and the amplitude of the total scattering section are also discussed in detail. The thermally averaged elastic rate coefficients at T = 10, 15, 20, 25 K are calculated and compared.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2022
The potential energy curves of the ground and five low-lying excited terms of the RaF molecule ar... more The potential energy curves of the ground and five low-lying excited terms of the RaF molecule are calculated using the Fock-space relativistic coupled theory. The electronic term energies, equilibrium internuclear distances, transition and permanent dipole moments, sequences of vibrational energies, harmonic vibrational frequencies, Franck-Condon factors, and radiative lifetimes are predicted. The calculated spectroscopic constants are in good agreement with the available theoretical and experimental data. The scheme for the direct laser cooling involving the first excited A2П1/2 state is proposed. The data obtained in this study suggests the A2П1/2 → X2Σ+ channel in the RaF molecule is the almost ideal case for direct laser cooling. It is quite possible that the effective cooling scheme for the RaF molecule can be realized using only one pump laser.
Abstract The potential energy curves of the ground and eight low-lying excited atomic and ionic t... more Abstract The potential energy curves of the ground and eight low-lying excited atomic and ionic terms of the RaCl molecule are calculated for the first time using the multi-reference perturbation theory method at the CASSCF/XMCQDPT2 level of theory including the spin-orbit coupling. The electronic term energies, equilibrium internuclear distances, dissociation energies, transition dipole moments, sequences of vibrational energies, harmonic vibrational frequencies, Franck–Condon factors, and radiative lifetimes are predicted. The data obtained in this study suggests the possibility of the direct laser cooling of the RaCl molecules.
Journal of Quantitative Spectroscopy and Radiative Transfer, 2021
Abstract The potential energy curves of the ground and five low-lying excited states of the RaBr ... more Abstract The potential energy curves of the ground and five low-lying excited states of the RaBr molecule are calculated using the Fock-space relativistic coupled cluster theory for the first time. A number of properties such as the electronic term energies, equilibrium internuclear distances, transition and permanent dipole moments, sequences of vibrational energies, harmonic vibrational frequencies, Franck–Condon factors, and radiative lifetimes are predicted. The results of this study show that RaBr molecules can be used for the direct laser cooling. The comparison to the previous theoretical studies of the RaF and RaCl molecules is also provided.
Based on a high level ab initio calculation which is carried out with the multireference configur... more Based on a high level ab initio calculation which is carried out with the multireference configuration interaction method under the aug-cc-pVXZ (AVXZ) basis sets, X = T, Q, 5, the accurate potential energy curves (PECs) of the ground state X Σ g + 1 and the first excited state A Σ u + 1 of Li2 are constructed. By fitting the ab initio potential energy points with the Murrell–Sorbie potential function, the analytic potential energy functions (APEFs) are obtained. The molecular bond length at the equilibrium (R e ), the potential well depth (D e ), and the spectroscopic constants (B e , ω e , α e , and ω e χ e ) for the X Σ g + 1 state and the A Σ u + 1 state are deduced from the APEFs. The vibrational energy levels of the two electronic states are obtained by solving the time-independent Schrödinger equation with the Fourier grid Hamiltonian method. All the spectroscopic constants and the vibrational levels agree well with the experimental results. The Franck–Condon factors (FCFs) co...
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Papers by Maksim Shundalau