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- Belyaev, Andrey K., et al.
(author)
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Inelastic silicon-hydrogen collision data for non-LTE applications in stellar atmospheres
- 2014
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 572, s. A103-
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Journal article (peer-reviewed)abstract
- Aims. Inelastic processes in low-energy Si + H and Si+ + H- collisions are treated for the states from the ground state up to the ionic state, in order to provide rate coefficients needed for non-LTE modeling of Si in cool stellar atmospheres. Methods. Electronic molecular structure is determined using a recently proposed model approach based on an asymptotic method in combination with available ab initio potentials. Nonadiabatic nuclear dynamics are treated by means of a combination of multichannel formulas and the branching-probability-current method, based on the Landau-Zener model for nonadiabatic transition probabilities. Results. Cross sections and rate coefficients for inelastic processes in Si + H and Si+ + H- collisions for all transitions between 26 low-lying states plus the ionic state are calculated. It is shown that the highest rate coefficient values correspond to the excitation, de-excitation, ion-pair formation, and mutual neutralization processes involving the Si(3p4p D-3), Si(3p3d F-3), Si(3p4p D-1), Si(3p3d P-3), Si(3p4p S-1), and the ionic Si+ + H- states. These processes are likely to be important in non-LTE modeling.
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