Four-body classical study of H-H collisions

Abstract
The Classical Trajectory Monte Carlo (CTMC) method has been applied to the study of atomic hydrogen collisions. The classical dynamics consists here in a four-body Coulomb problem formulation involving two protons and two electrons. For each atom a microcanonical ensemble has been used for constituting the initial conditions of the trajectories. The asymmetry introduced in the calculations by giving to the projectile atom initial positions with variable impact parameter b values in relation with the target one, is waived by the correct statistical treatment, in accordance with the physical symmetry of the collision. In the studied collision energy region, 5 to 200 keV, the obtained values compare favorably with existing experimental data and quantal calculations. For low energies, the integration of trajectories corresponding to the cases of ionization (direct and transfer ionization of the projectile and of the target), has to be improved in order to comply with the well-known problem of the "saddle points".