Theoretical calculation of spectroscopy properties of selenium bromide cation.

In this paper, the potential energy curves of 22 Λ-S states as well as 51 Ω states were calculated using the internally contracted multiconfiguration interaction and Davidson correction method. Through the obtained transition data, the spectroscopy data of the low excitation bound state are fitted and compared with the same main group ions. The phenomenon of avoided crossing that occurs in the Ω state is analyzed, and finally it is concluded that this phenomenon mainly occurs in the energy region between 20 000 cm-1 and 40 000 cm-1. The potential laser cooling transition cycle in the Ω state is analyzed. The Franck-Condon factor, radiative lifetime and Einstein coefficient between are calculated. In this paper, we argue that direct laser cooling of SeBr+ is not feasible. The content of our study provides a theoretical basis for subsequent calculations to explore the properties of SeBr+ spectrum.

Theoretical Study on the Electronic Structure and Transition Properties of Low Excited States of SeCl.

For the first time, the spectroscopy and transition properties of SeCl+ are systematically reported. The potential energy curves of 22 Λ - S states and the corresponding 51 Ω states in the first and second dissociation channels of SeCl+ are calculated using the internally contracted multiconfiguration interaction and Davidson correction method. The phenomenon of avoided crossing in Ω states below 30,000 cm-1 is discussed in detail. The spectroscopy constants are obtained by fitting the potential energy curves, and also the Franck-Condon factors and radiation lifetimes of the X3Σ0+- ↔ 21Σ0++ transition are calculated. Between X3Σ0+- and 21Σ0++, the Franck-Condon factors are large, close to 1, but the radiation lifetime is large too. According to the calculation results, it is determined that direct laser cooling of SeCl+ is considered infeasible.

Study on the spectroscopy and transition properties of TeCl.

For the first time, the spectroscopy data of TeCl+ ion and the transition data between low excited states are systematically calculated. The potential energy curves of 22 Λ-S states and 51 Ω states are calculated by the internally contracted multiconfiguration interaction and Davidson correction method. By solving the one-dimensional radial Schrödinger equation, the spectroscopy data of Λ-S states and Ω states are obtained. The phenomenon of avoided crossing in Ω state is analyzed in detail, which is mainly concentrated in the region of 20000 cm-1 to 35000 cm-1. The Franck-Condon factors, Einstein coefficients and spontaneous radiative lifetimes of [Formula: see text] transitions are calculated. According to the calculation results, it is preliminarily judged that the direct laser cooling of TeCl+ ion is not feasible.

Theoretical study of the low-lying electronic states, including the spin-orbit interactions, of the sulfur monochloride cation.

High-level ab initio computations have been performed on the experimentally unknown species SCl+. The low-lying Λ-S electronic states correlated to the first and the second dissociation channels as well as their corresponding Ω states have been investigated by the icMRCI+Q methodology employing basis sets up to quintuple-ζ quality. Information about potential energy curves, electron configurations, spectroscopic constants, dipole moments and transition properties are derived and discussed. The results for SCl+ represent an improvement over our previous theoretical descriptions for the ground state. In addition, several low-lying excited states that have not been accessed experimentally and theoretically are also been well characterized in this work. The accuracy of our predictions for SCl+ are verified by comparisons of spectroscopic constants and vibrational levels between our accompany SCl computations and those reported in literatures for the neutral species. The feasibility of performing laser cooling of SCl+ has also been discussed and the photoelectron spectrum of SCl+(X3Σ-) + e â† SCl(X2Π) is simulated.

Ab initio investigation on the low-lying electronic states of magnesium antimonide.

The twelve Λ-S electronic states of the first four dissociation limits of the MgSb molecule have been examined at the icMRCI+Q level employing basis sets of quintuple-ζ quality. The potential energy curves, vibrational levels and spectroscopic constants of the species have been investigated. The permanent dipole moments of the interested states are derived, and the transition dipole moments, Einstein emission coefficients, radiation lifetimes and Franck-Condon factors between selected states are also determined. Four Λ-S states of the first two dissociation limits split into seven Ω states under the effect of spin-orbit coupling. Characterizations of the MgSb low-lying Ω states are performed for the first time. In addition, the results and relevant data provided in this work on MgSb are compared with the antimony-IIA group and magnesium-VA group diatomic species. It is anticipated that this work will shed some light on further investigations of MgSb and other antimony-IIA group systems.

The study of laser cooling of TeH- anion in theoretical approach.

The probabilities of laser cooling of TeH- anion via a spin-forbidden transition and a three-electronic-level transition are proposed. The potential energy curves of the X1Σ+, a3∏, A1∏, and b3Σ+ electronic states of tellurium monohydride anion (TeH-) are calculated using multi-reference configuration interaction method. Davidson corrections, core-valence correlations and spin-orbit coupling effects are also considered. The AWCV5Z-PP pseudopotential basis set of Te atom is used. Spectroscopic parameters of the Λ-S and Ω states are obtained by solving radial Schrodinger equation. These results are reported at the first time. Permanent dipole moments of the Ω states and transition dipole moments of the a21↔X0+ and A1↔X0+ transitions are also calculated. Highly diagonally distributed Franck-Condon factors of the a21↔X0+ and A1↔X0+ transitions are obtained, the value of f00 is 0.9970 and 0.9980, respectively. Spontaneous radiative lifetimes of the a21 and A1 excited states are predicted. i.e. τ(a21) = 200.3 ns and τ(A1) = 84.3 ns. Only the main pump laser is required to driving a21↔X0+ and A1↔X0+ transitions. The laser wavelengths both are in the visible region. Doppler temperatures and recoil temperatures of laser cooling TeH- anion are also predicted.

Characterization of the low-lying electronic states of tin monohydride cation including the spin-orbit coupling effect: A theoretical perspective.

High-level ab initio computations have been performed on SnH+. The potential energy curves and spectroscopic constants of the low-lying Λ-S electronic states, as well as their associated Ω states, are derived at the icMRCI + Q level employing basis sets of quintuple-ζ quality. The transition dipole moments, Einstein coefficients, radiative lifetimes and Franck-Condon factors of three spin-forbidden transition bands ( [Formula: see text] , [Formula: see text] and [Formula: see text] ) are determined. Comparisons between our predictions and available experimental results indicate reasonable agreement. The spin-orbit coupling effect has been proved to affect these low-lying electronic states significantly.

Theoretical investigation on the low-lying electronic states of beryllium antimonide.

The Λ-S electronic states with respect to the lowest four dissociation limits of BeSb are investigated theoretically on the icMRCI + Q level employing basis set of quintuple-ζ quality. The geometrical parameters, potential energy curves, vibrational energy levels, spectroscopic constants for the twelve Λ - S states are obtained, analyzed and compared with those of the Beryllium-VA group diatomic family species where data are available. The permanent dipole moments, transition dipole moments, Einstein emission coefficients, radiative lifetimes and Franck-Condon factors for interested Λ - S states are also derived. Further assessments of the spin-orbit coupling effect are performed for states associated with the first two dissociation asymptotes of BeSb. Four Λ - S states split into seven Ω states, and some of the PECs are distorted significantly through the spin-orbit coupling effect, which is similar to its isovalent diatomics BeAs. In consideration of potential risks of manipulating beryllium-containing species directly, the information associated with molecular structures, spectroscopic parameters as well as transition properties that provide in this paper is anticipated to serve as guidelines for further researches of BeSb.

An ab initio investigation on the low-lying electronic states of NaMg.

Theoretical investigations for NaMg have been performed on the icMRCI + Q level employing basis set of quintuple-ζ quality with corrections of core-valence correlation and scalar relativistic effect. The geometrical parameters, potential energy curves, vibrational energy levels, spectroscopic constants for the eight Λ-S states, with respect to the lowest four dissociation limits, are investigated. Through the spin-orbit coupling effect, these states split into fourteen Ω states. The permanent dipole moments, transition dipole moments, Einstein emission coefficients, radiative lifetimes and Franck-Condon factors for all Ω states are studied. The feasibility of performing laser cooling of NaMg has also been discussed. Our predictive results are anticipated to serve as guidelines for further researches on NaMg.

Laser cooling of the OH- molecular anion in a theoretical investigation.

The schemes for laser cooling of the OH- anion are proposed using an ab initio method. Scalar relativistic corrections are considered using the Douglas-Kroll Hamilton. Spin-orbit coupling (SOC) effects are taken into account at the MRCI+Q level. SOC effects play important roles in the transition properties of the OH- anion. Transition strengths for the transition of the OH- anion cannot be ignored. Large vibrational branching ratios for the and transitions are determined. Short spontaneous radiative lifetimes for the a3Π1 and A1Π1 states are also predicted for rapid laser cooling. The vibrational branching loss ratio to the intervening states a3Π0 and a3Π1 for the transition is small enough to enable the building of a laser cooling project. The three required laser wavelengths for the and transitions are all in the visible region. The results imply the probability of laser cooling of the OH- anion via both a spin-forbidden transition and a three-electronic-level transition.

Theoretical investigation on spin-forbidden cooling transitions of gallium hydride.

Herein, the spin-forbidden cooling of a gallium hydride molecule is investigated using ab initio quantum chemistry. The cooling transition and the corresponding potential energy curves including , a3Π0-, a3Π0+, a3Π1, a3Π2, A1Π1, , 13Σ, , , and 23Σ states are simulated based on the multi-reference configuration interaction approach plus Davidson corrections method. By solving the nuclear Schrödinger equation, we calculate the spectroscopic constants of these states, which are in good agreement with the available experimental values. Based on the transition data, there seems to be a theoretical puzzle: highly diagonally distributed Franck-Condon factor f00 for transitions , , and for the gallium hydride molecule but the intervening state A1Π1 for transition is prohibitive to laser cooling. In addition, the transition does not have a suitable rate of optical cycling owing to a large radiative lifetime for state. Our theoretical simulation indicates the solution to the puzzle: the transition has a high emission rate, and there is a suitable radiative lifetime for a3Π1 state, which can ensure rapid and efficient laser cooling of gallium hydride. The proposed laser drives transition by using three wavelengths (main pump laser λ00; two repumping lasers λ10 and λ21). These results demonstrate the possibility of laser-cooling the gallium hydride molecule, and a sub-microkelvin cool temperature can be reached for this molecule.

Laser cooling of BeCl and BeBr molecules in an ab initio method.

In this study, the feasibility of laser-cooling of BeCl and BeBr molecules is studied using ab initio quantum chemistry. The potential energy curves for the X(2)Σ(+), A(2)Π, and 2(2)Π electronic states of BeCl and BeBr are plotted based on multi-reference configuration interaction plus Davidson corrections (MRCI + Q), and the spin-orbit coupling (SOC) effects are considered at the MRCI + Q level. The calculated spectroscopic parameters agree with the experimental data. Highly diagonally distributed Franck-Condon factors are determined for the A(2)Π(ν' = 0) ← X(2)Σ(+)(ν'' = 0) transition: f00(BeCl) = 0.947 and f00(BeBr) = 0.966. Moreover, the suitable radiative lifetimes τ of the A(2)Π(ν' = 0) state are determined for rapid laser cooling: τ(BeCl) = 18.38 ns and τ(BeBr) = 27.09 ns. The proposed cooling wavelengths of both BeCl and BeBr are within the ultraviolet region at λ00(BeCl) = 358.51 nm and λ00(BeBr) = 379.38 nm. Laser cooling schemes for BeCl and BeBr molecules are also developed in consideration of the SOC effects. These results indicate that the inclusion of SOC effects does not affect the judgment of the feasibility of laser cooling of BeCl and BeBr molecules, even for the given BeBr molecules in which the SOC effect is significant.

Transport coefficients and entropy-scaling law in liquid iron up to Earth-core pressures.

Molecular dynamics simulations were applied to study the structural and transport properties, including the pair distribution function, the structure factor, the pair correlation entropy, self-diffusion coefficient, and viscosity, of liquid iron under high temperature and high pressure conditions. Our calculated results reproduced experimentally determined structure factors of liquid iron, and the calculated self-diffusion coefficients and viscosity agree well with previous simulation results. We show that there is a moderate increase of self-diffusion coefficients and viscosity along the melting curve up to the Earth-core pressure. Furthermore, the temperature dependencies of the pair correlation entropy, self-diffusion, and viscosity under high pressure condition have been investigated. Our results suggest that the temperature dependence of the pair correlation entropy is well described by T(-1) scaling, while the Arrhenius law well describes the temperature dependencies of self-diffusion coefficients and viscosity under high pressure. In particular, we find that the entropy-scaling laws, proposed by Rosenfeld [Phys. Rev. A 15, 2545 (1977)] and Dzugutov [Nature (London) 381, 137 (1996)] for self-diffusion coefficients and viscosity in liquid metals under ambient pressure, still hold well for liquid iron under high temperature and high pressure conditions. Using the entropy-scaling laws, we can obtain transport properties from structural properties under high pressure and high temperature conditions. The results provide a useful ingredient in understanding transport properties of planet's cores.