A theoretical study of Ne3 using hyperspherical coordinates and a slow variable discretization approach

Cold atom-atom-anion three-body recombination of 4He4HexLi- (x = 6 or 7) systems

Atom-atom-anion three-body recombination (TBR) in mixed ⁴He and ^xLi^- (x = 6 or 7) is investigated in the adiabatic hyperspherical representation by quantum mechanically solving the Schrödinger equation. The distributions of product states following these TBR processes are found to be relatively different for the two systems when the collision energy is less than roughly 0.6 mK × k_B or 0.3 mK × k_B for ⁴He⁴He⁶Li^- and ⁴He⁴He⁷Li^- systems, respectively, with k_B being the Boltzmann constant. For ⁴He⁴He⁶Li^- systems, the rate of recombination into (v=0) l = 0⁴He⁶Li^- molecular anions is the largest with v and l denoting the rovibrational quantum numbers, while the TBR rate that leads to the formation of l = 1⁴He⁶Li^- molecular anions is a little smaller than that of neutral ⁴He₂ molecules. For ⁴He⁴He⁷Li^- systems, neutral ⁴He₂ molecules tend to be the most products, following the yields of l = 0 and 1 ⁴He⁷Li^- molecular anions. However, in spite of these distinctly different distributions, the products of molecular anions, the sum of l = 0 and 1 ⁴He^xLi^- products, are relatively larger than that of neutral ⁴He₂ molecules for both the two systems.

Role of sharp avoided crossings in short hyper-radial range in recombination of the cold 4He3 system

The role of sharp avoided crossings (SACs) in a short hyper-radial range R≤ 50 a.u. in the calculation of recombination for a cold ⁴He₃ system is investigated in the adiabatic hyperspherical representation by "turning off and on" the relevant nonadiabatic couplings. The influence of SACs on the recombination is related with the channels of the system and with the scattering energy. For J^Π = 0⁺ symmetry, the two-body recombination channel has an attractive potential well, which makes radial wave functions of both two-body recombination channel and three-body continuum channels accessible in the short hyper-radial range where SACs are located. The SACs consequently play an important role in coupled-channel calculations and this is particularly the case for lower scattering energies. However, for excited nuclear orbital momenta, i.e., J^Π = 1^-, 2⁺,…, 7^- symmetries, the two-body recombination channel has a repulsive interaction and the radial wave functions are not accessible in the short hyper-radial range. Therefore, omission of SACs in the short range for these symmetries has no effect on the numerical results, which leads to great savings on hyper-radial grid points in the practical numerical calculations. Moreover, to make the nonadiabatic couplings among channels to be continuous in the hyper-radius, different methods associated with the application of consistent phase convention are discussed.

ROVIBRATIONAL BOUND STATES OF THE Ar2Ne COMPLEX

We report exact quantum dynamics calculations of the eigenstate energy levels for the bound rovibrational states of the Ar2Ne complex, across the range of J values for which such states are observed (J = 0–35). All calculations have been carried out using the ScalIT suite of parallel codes. These codes employ a combination of highly efficient methods, including phase-space optimized discrete variable representation, optimal separable basis, and preconditioned inexact spectral transform (PIST) methods, together with an effective massive parallelization scheme. The Ar2Ne energy levels were computed using a pair-wise Aziz potential plus a three-body correction, in Jacobi co-ordinates. Effective potentials for the radial co-ordinates are constructed, which reveal important physical insight into the two distinct dissociation pathways, Ar2Ne → NeAr + Ar and Ar2Ne → Ar2 + Ne . A calculation of the bound vibrational (J = 0) levels, computed using the Tang–Toennies potential, is also performed for comparison with results from the previous literature.