Dynamics of excitation and electron capture processes in the H+ + H(1s) collision system in a Debye plasma is studied as an example of collision systems with screened Coulomb interactions. The two-centre atomic orbital close-coupling method (TC-AOCC) was used with a basis containing all n ⩽ 6 and 7s discrete and 99 quasi-continuum states centred on the target and all n ⩽ 3 discrete states centred on the projectile when describing the excitation process, and vice versa when describing the electron capture. The atomic orbitals and energies of all one-centre states have been determined variationally as a function of screening parameter and used to calculate the state-selective electron capture and excitation cross sections. With an increase of the screening, the bound states successively enter the continuum, thereby reducing the number of reaction channels in the discrete spectrum. The effect of interaction screening on the direct and exchange electronic couplings is also strong. Both these factors significantly affect the dynamics of electron capture and excitation processes. The interaction screening parameter can, thus, be used as a tool for control of the collision dynamics.

The charge transfer process in C5+-H collisions has been theoretically studied using the two-center atomic orbital close-coupling method in the energy interval from 0.1 to 300 keV u−1. The interaction of active electron with the projectile ion is represented by model potentials different for the singlet and triplet systems of C4+(1snl) states. The results of the present calculations are compared with other theoretical results and experimental measurements and good agreement is obtained for the total spin-averaged cross sections in the overlapping energy range. For the spin-resolved cross sections, we found that the present total and n-shell electron capture cross sections are also in good agreement with the results of other theoretical studies in the overlapping energy range for both the singlet and triplet cases. Good overall agreement has been obtained with the results of other authors for the nl-state-selective cross sections, except for the capture to 3p and 4p singlet states at the low collision energies.

The electron capture and excitation processes in collisions of He+-Li are investigated theoretically by using the two-center atomic orbital close-coupling method in the energy range 0.1–100 keV u−1. The interaction of active electrons with the projectile ion is represented by a model potential different for the singlet and triplet systems of He states. The spin-averaged electron capture cross section of present calculations is compared with the available experimental data and with the results of other theoretical calculations and good agreement is obtained in the overlapping energy range. It is found that the cross sections for electron capture to singlet and triplet states of He are significantly different for energies below 5 keV u−1. However, the spin-resolved He+-Li interactions do not affect the excitation cross sections considerably.