Theoretical calculations of rotationally inelastic collisions of He with NaK(A {sup 1}Σ{sup +}): Transfer of population, orientation, and alignment
- Laboratoire Univers et Particules de Montpellier, UMR 5299, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier (France)
We have performed extensive calculations to investigate thermal energy, rotationally inelastic collisions of NaK (A{sup 1}Σ{sup +}) with He. We determined a potential energy surface using a multi-reference configuration interaction wave function as implemented by the GAMESS electronic structure code, and we have performed coupled channel scattering calculations using the Arthurs and Dalgarno formalism. We also calculate the Grawert coefficients B{sub λ}(j, j′) for each j → j′ transition. These coefficients are used to determine the probability that orientation and alignment are preserved in collisions taking place in a cell environment. The calculations include all rotational levels with j or j′ between 0 and 50, and total (translational and rotational) energies in the range 0.0002–0.0025 a.u. (∼44–550 cm{sup −1}). The calculated cross sections for transitions with even values of Δj tend to be larger than those for transitions with odd Δj, in agreement with the recent experiments of Wolfe et al. (J. Chem. Phys. 134, 174301 (2011)). The calculations of the energy dependence of the cross sections and the calculations of the fraction of orientation and alignment preserved in collisions also exhibit distinctly different behaviors for odd and even values of Δj. The calculations also indicate that the average fraction of orientation or alignment preserved in a transition becomes larger as j increases. We interpret this behavior using the semiclassical model of Derouard, which also leads to a simple way of visualizing the distribution of the angles between the initial and final angular momentum vectors j and j′. Finally, we compare the exact quantum results for j → j′ transitions with results based on the simpler, energy sudden approximation. That approximation is shown to be quite accurate.
- OSTI ID:
- 22415965
- Journal Information:
- Journal of Chemical Physics, Vol. 142, Issue 22; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
ANGULAR MOMENTUM
ATOM-MOLECULE COLLISIONS
CONFIGURATION INTERACTION
COUPLED CHANNEL THEORY
CROSS SECTIONS
ELECTRONIC STRUCTURE
ENERGY DEPENDENCE
HELIUM
POTASSIUM ALLOYS
POTENTIAL ENERGY
PROBABILITY
SCATTERING
SEMICLASSICAL APPROXIMATION
SODIUM ALLOYS
SUDDEN APPROXIMATION
SURFACES
VECTORS
WAVE FUNCTIONS