Molecule opacities of X^2Σ^+, A^2Π, and B^2Σ^+ states of CS^+

Carbon sulfide cation(CS^+) plays a dominant role in some astrophysical atmosphere environments. In this work, the rovibrational transition lines are computed for the lowest three electronic states, in which the internally contracted multireference configuration interaction approach(MRCI) with Davison size-extensivity correction(+Q) is employed to calculate the potential curves and dipole moments, and then the vibrational energies and spectroscopic constants are extracted. The Frank–Condon factors are calculated for the bands of X^2^+Σ^+–A^2Π and X^2Σ^+–B^2Σ^+systems, and the band of X^2Σ^+–A^2Π is in good agreement with the available experimental results. Transition dipole moments and the radiative lifetimes of the low-lying three states are evaluated. The opacities of the CS^+ molecule are computed at different temperatures under the pressure of 100 atms. It is found that as temperature increases, the band systems associated with different transitions for the three states become dim because of the increased population on the vibrational states and excited electronic states at high temperature.

Molecular opacities of low-lying states of oxygen molecule

The X^3Σg^-,A^'3△u,A^3Σ^u+,1^3Πg,and B^3Σu^-electronic states of oxygen molecule(O2)are calculated by the multiconfiguration self-consisted filed(MRCI)+Q method with the scalar relativistic correction and core-valence correlation correction.The obtained spectroscopic constants of the low-lying bound states are in excellent agreement with measurements.Based on the accurately calculated structure parameters,the opacities of the oxygen molecule at the temperatures of 1000 K,2000 K,2500 K,and 5000 K under a pressure of 100 atm(1 atm=1.01325×10^5 Pa)and the partition functions between 10 K and 10^4 K are obtained.It is found that with the increase of temperature,the opacities for transitions in a long wavelength range are enlarged because of the larger population on excited electronic states at the higher temperatures.

Ab Initio Study of Single-and Double-Electron Capture Processes in Collisions of He^(2+) Ions and Ne Atoms

The single-and double-electron capture(SEC, DEC) processes of He^(2+) ions colliding with Ne atoms are studied by utilizing the full quantum-mechanical molecular-orbital close-coupling method. Total and state-selective SEC and DEC cross sections are presented in the energy region of 2 eV/u to 20 keV/u. Results show that the dominant reaction channel is Ne^(+)(2s2p^(6) ^(2)S) + He^(+)(1s) in the considered energy region due to strong couplings with the initial state Ne(2s^(2)2p^(6)^(1)S) + He^(2+) around the internuclear distance of 4.6 a.u. In our calculations, the SEC cross sections decrease initially and then increase whereby, the minimum point is around 0.38 keV/u with the increase of collision energies. After considering the effects of the electron translation factor(ETF), the SEC cross sections are increased by 15%–25% nearby the energy region of keV/u and agree better with the available results. The DEC cross sections are smaller than those of SEC because of the larger energy gaps and no strong couplings with the initial state. Due to the Demkov-type couplings between DEC channel Ne^(2+)(2s^(2)2p^(4)^(1)S) + He(1s^(2)) and the dominating SEC channel Ne^(+)(2s2p^(6) ^(2)S) + He^(+)(1s), the DEC cross sections increase with increasing impact energies. Good consistency can also be found between the present DEC and the experimental measurements in the overlapping energy region.

Charge transfer and excitation processes in low energy collisions of He ions with Li atoms

Electron capture between solar wind ions and neutral species has contributed to the understanding of X-ray production from solar system bodies.The charge transfer and excitation processes in solar wind ions of He^(+)(1 s) colliding with Li(1 s^(2)2 s) atoms are studied by utilizing the full quantum-mechanical molecular-orbital close-coupling(QMOCC) method with impact energies of 0.003-2 keV amu-1.Comparisons of cross sections from single-and multi-configurational calculations for a selfconsistent field(SCF and MCSCF) process are carried out.Results show that the dominant reaction channels are He(1 s2 l ^(1,3) L)+Li^(+)(1 s^(2) ^(1) S).Good consistency is found among present total and state-selective charge transfer and excitation cross sections with other theoretical and experimental data in the same energy region.Due to the differences between coupling matrix elements in high-energy states,the charge transfer cross sections calculated from SCF and MCSCF split slightly as E> 0.4 keV amu-1.Weak Stueckelberg oscillations for charge transfer appear in the present work.In addition,the differences of cross sections for electron excitation to Li(ls^(2)2 p) in the singlet/triplet molecular states with He+(1 s) are much smaller than those of charge transfer processes because of the similar energy gaps from Li(ls^(2)2 p) to the ground state in singlet/triplet states in the large R region.

Molecular Opacity Calculations for Lithium Hydride at Low Temperature

The opacities of the lithium hydride molecule are calculated for temperatures of 300 K,1000 K,1500 K,and 2000 K,at a pressure of 10 atm,in which the contributions from the five low-lying electronic states are considered.The ab initio multi-reference single and double excitation configuration interaction(MRDCI)method is applied to compute the potential energy curves(PECs)of the 7 LiH,including four 1∑+states and one 1Πstate,as well as the corresponding transition dipole moments between these states.The ro-vibrational energy levels are calculated based on the PECs obtained,together with the spectroscopic constants.In addition,the partition functions are also computed,and are provided at temperatures ranging from 10 K to 2000 K for 7 LiH,7 LiD,6 LiH,and 6 LiD.