Quantum and semi-classical collision cross-sections and transport data for a Kr⁺/Kr system

Abstract

Krypton ion transport properties in krypton carrier gas have been calculated using various methods and two state-of-the-art sets of diatomic interaction potentials and compared to available experimental data. First, momentum transfer effective cross-sections have been calculated for Kr + /Kr collisions for the ion in either of two fine-structure states ( P 2 3 2 and P 2 1 2 ). A full quantum approach, semi-classical approximation, and a hybrid method (classical treatment of nuclei and quantum description of electrons) have been used. Then, an optimized Monte Carlo code has been employed to calculate the basic transport parameters (mobility and diffusion coefficients) of the Kr + ion in the carrier krypton gas. A thorough comparison of the calculated data with available experiments allowed the assessment of the reliability of the interaction models and methodologies to be used in further calculations. In addition, theoretical predictions are provided for these coefficients where they are not available from measurements.

Non-adiabatic dynamics combining Ehrenfest, decoherence, and multiscale approaches applied to ionic rare-gas clusters photodissociation, post-ionization fragmentation, and collisions

“…Since the inter-group transitions are rather improbable, a concept of pseudo-ground state for the excited state group could be introduced. Some comparisons made with full quantum results (in the context of cold plasmas modeling) [75,80] are very encouraging, although some differences remain related to the classical treatment of the nuclear motion for helium [75] and involved effects for the heavier rare gases [80].…”

Calculations with experimental validations of cross-sections and transport coefficients of Xe+ colliding with Xe

“…The methodology used here was described in detail in a previous paper focused on Kr Kr + collisions [16] and, thus, just a short summary is provided here. Interested readers are referred to the Kr Kr + work and the references cited therein.…”

“…Within the full quantum approach, the scattering amplitude is obtained by numerically solving the stationary Schrödinger equation [18], while much less demanding calculations are used within the semi-classical method adopting the JWKB approximation [19]. Since the colliding particles may be identical or different isotopes (distinguishable or not) and since they may be of both types, bosonic or fermionic, specific symmetry considerations [19] must be followed when calculating the scattering amplitudes as described in the preceding Kr Kr + paper [16] or in [13].…”

“…Within this approach, electrons are treated via the time dependent Schrödinger equation while nuclei undergo classical evolution under the action of a mean force resulting from current electronic wave function. Bunches of collision trajectories are solved for each collision energy, with the initial conditions set appropriately [16], and the differential cross-section is then obtained from j N 1 lim , 2 sin , 4…”

“…No systematic investigation on the dependence of the calculated data either on the approximations made or on the interaction models used was performed. The main aim of the present work is to partly fill this gap by extending our previous calculations done on atomic ions of helium [14], argon [15], and krypton [16].…”