Multicrossing Landau-Zener and close-coupling calculations of electron transfer in collisions

Abstract

Cross sections for electron capture from Li(2s,2p) by proton impact have been calculated for energies in the range 10 eV-10 keV within the atomic orbital close-coupling (AO-CC) and the multicrossing Landau-Zener (MLZ) one-electron models. For the excited Li(2p) target the long-range mixing of the magnetic sublevels has been included in the MLZ calculations by means of a locking-radius model. The MLZ approximation to the AO-CC calculations is found to be appropriate at energies of about 10 eV. When diagonalizing the effective electronic Hamiltonian within the close-coupling basis a non-physical potential curve is disclosed. The cross section for capture from Li(2s) in particular is shown to be sensitive to this curve for energies below 50 eV. It is demonstrated how this problem is eliminated by including a pseudo-Li(1s) state in the AO-CC basis set.

Cross sections for electron capture in H+-Li(2pσ,π±) collisions

“…In the calculations of other authors (Refs. [4][5][6][7][8]) such state-selective cross sections are not reported. It is to be noted in this figure that the present QMOCC and AOCC results for capture to the 2s and 2p state of H are in a fairly good mutual agreement in the overlapping energy range.…”

“…In Refs. [5,6,8,10], only the half-sum of the populations of these states from Li(2pπ + ) and Li(2pπ − ) initial states is given.…”

“…On the theoretical side, this process has been subject to many theoretical studies using various methods to describe its dynamics. Large-scale semiclassical close-coupling (CC) cross-section calculations have been performed by using the atomic orbital closecoupling (AOCC) [4,5] and molecular orbital close-coupling (MOCC) [6][7][8][9] methods, as well as the numerical solution of the time-dependent Schrödinger equation (TDSE) [10].…”

Electron capture and excitation processes in the Li(2s; 2pσ, 2pπ)+H+collision (0.1-10 keV)

“…The molecular wavefunctions are built as a linear combination of two-centre STO atomic orbitals. Lundsgaard et al (1998) used an atomic orbital close-coupling model (including translation factors to ensure the Galilean invariance) as well as a multicrossing Landau-Zener model. Their calculations include a state number similar to that of the present work.…”

Ionization channel in non-perturbative ion-atom collisions dominated by charge exchange

“…A large number of studies has been performed using these codes, most recently e.g. [15]. and the paper [1] mentioned as one of the motives for this work.…”