Heavy-ion Collisions The Process Of Theoretical Research

Heavy-particle collisions play an important role in astrophysical and laboratory plasma. Due to the difficulties on many-body and multicenter problem, it is still a hot and frontier field in atomic and molecular physics. In this thesis, firstly, the researches on heavy-particle collisions are briefly reviewed, and especially, some theoretical methods are introduced. Then, we focus on the studies of the classical trajectory Monte Carlo (CTMC) method. Using the CTMC method, the impact ionization of Si²⁺ with H is investigated in the collision energies from 1keV/u to 10MeV/u. Total cross sections, single- and double-differential cross sections are obtained as the functions of the incident energies, the ejected-electron energies and/or angles, respectively. The ionization mechanisms of soft collision, electron capture to the continuum state, binary-encounter collision are displayed. However, for the collision processes in He target, a large discrepacy between the CTMC results and experimental measurement is found. As is well known, the microcanonical distributions of bounded electrons in CTMC method is quite different from quantal distributions, we modified the initial microcanonical distribution by using eleven different ionization thresholds of electron bounded in target. With modification, we calculated the collisional process of O³⁺ with He, and the total cross sections of all processess are calculated as a function of the incident energies. The agreement with experiments is improved by the modified distributions. In chapter4-6, we studied the mutual neutralization of H₂⁺ + H^-, H₃⁺ + H^-, Si⁺ + H^- inslow collisions within the semi-classical multi-channel Landau-Zener (MCLZ) model. The cross sections for electron capture to specific states (singlet and triplet) are calculated. The calculated total mutual neutralization cross section is in satisfactory agreement with the available experimental data.