A. Amaya-Tapia

KANTBP: A program for computing energy levels, reaction matrix and radial wave functions in the coupled-channel hyperspherical adiabatic approach

A FORTRAN 77 program is presented which calculates energy values, reaction matrix and corresponding radial wave functions in a coupledchannel approximation of the hyperspherical adiabatic approach. In this approach, a multi-dimensional Schrodinger equation is reduced to a system of the coupled second-order ordinary differential equations on the finite interval with homogeneous boundary conditions of the third type. The resulting system of radial equations which contains the potential matrix elements and first-derivative coupling terms is solved using high-order accuracy approximations of the finite-element method. As a test desk, the program is applied to the calculation of the energy values and reaction matrix for an exactly solvable 2D-model of three identical particles on a line with pair zero-range potentials. Program summary

Second virial coefficient in one dimension as a function of asymptotic quantities

A result from Dodd and Gibbs (J. Math. Phys., 15, 41 (1974)) for the second virial coefficient of particles in one dimension, subject to delta-function interactions, has been obtained by direct integration of the wave functions. It is shown that this result can be obtained from a phase shift formalism, if one also includes the contribution of oscillating terms. The result is important in work to follow, for the third virial coefficient, for which a similar formalism is being developed. We examine a number of fine points in the quantum mechanical formalisms.

Charge transfer of positive hydrogen ions and Ca vapour at keV energies

Total and partial single-electron-capture cross sections for H+ + Ca collisions have been calculated by the semiclassical impact-parameter method. A two-centre atomic basis expansion was used in the impact ion energy range 1–100 keV. The present total cross sections are in good agreement with previous experimental data. The most important contributions to the total cross sections come from the capture in the n = 2 shell in almost the entire energy range studied in this work, but the contribution from the n = 1 level is increasingly important at energies higher than 60 keV.

Single-electron capture cross section in 1-500 keV H+-Mg collisions

Total and partial cross sections for single-electron capture of H+ on Mg atoms have been calculated by the semi-classical impact-parameter method, using a two-centre atomic basis expansion, for energies between 1 and 500 keV. The present cross sections are in good agreement with previous experimental data over the wide energy range considered in this paper. The calculated capture cross section into the 2s state of hydrogen reproduces the main qualitative features observed experimentally but quantitatively overestimates the experimental measurements by a factor of four. However, our calculations show, for the first time, that capture into the n = 2 levels of hydrogen could be as important as capture into the ground state.

Experimental and theoretical investigations of single-electron capture and loss in He + -Ar collisions

Experimental and theoretical investigation of single-electron capture and additional experimental studies of single-electron loss cross sections in He+-Ar collisions at impact energies of 1.5-5.0 keV for experimental studies and from 10 to 4000 keV for the theoretical calculations are presented. Comparisons are made with other experimental results, for single-electron capture the present measurements confirm the behaviour observed by previous measurements in the energy range 1.5-5.0 keV, except with the data of Eisele and Nagy (1977 J. Chem. Phys. 66 883-5), and for single-electron loss an extrapolation of the high-energy results to low energies shows good agreement with the present data, giving the general shape of the cross section curve. Our theoretical calculations are in good agreement with the experimental data and reproduce the main features of the cross section energy dependence. We present the most important contributions to the total cross sections from the partial capture cross section to the He(1s) and He(n = 2) states, with the former as the dominant channel over the energy region considered.

ECC in proton-H collisions at keV projectile energy

Electron capture to the continuum is studied within a close-coupling approach, for proton-H collisions at keV projectile energy.

Differential, partial and total electron capture cross sections in p-Ar collisions

We discuss the results, from two approaches, on electron capture processes in p+Ar collisions: one based on a single-particle approximation, and the other, on a full electron-nuclear dynamics approach. This work presents differential, total and state to state single electron capture and double electron capture in the energy range from 10 eV to 100 keV. When appropriate we compare the results coming from the two methods, which leads us to discuss the effect of the straight line trajectory approximation and the interference effects in cross sections by different projectile trajectories that have the same scattering angle.