Frozen Core Approximation and Nuclear Screening Effects in Single Electron Capture Collisions

Abstract

Fully Differential Cross Sections (FDCS) for single electron capture from helium by heavy ion impact are calculated using a frozen core 3-Body model and an active electron 4-Body model within the first Born approximation. FDCS are presented for H + , He 2+ , Li 3+ , and C 6+ projectiles with velocities of 100 keV/amu, 1 MeV/amu, and 10 MeV/amu. In general, the FDCS from the two models are found to differ by about one order of magnitude with the active electron 4-Body model showing better agreement with experiment. Comparison of the models reveals two possible sources of the magnitude difference: the inactive electron's change of state and the projectile-target Coulomb interaction used in the different models. Detailed analysis indicatesthat the uncaptured electron's change of state can safely be neglected in the frozen core approximation, but that care must be used in modeling the projectile-target interaction.

One-center close-coupling approach to two-center rearrangement collisions

“…Depending on the incident energy of the projectile various theoretical models have been developed. Adiabatic hyperspherical [1] and molecularorbital close-coupling [2] methods are reliable at low energies, whereas the perturbative methods, such as the first Born approximation [3], the first Born with corrected boundary conditions [4] and continuum distorted-wave approaches [5][6][7] are successfully used at sufficiently high incident energies. There are a number of methods applicable in the intermediate energy region.…”

“…There are a number of methods applicable in the intermediate energy region. These are classical-trajectory Monte Carlo methods [8][9][10], a time-dependent density-functional theory [11] and approaches based on the close-coupling formalism 3 Author to whom any correspondence should be addressed. like a basis-generator method [12,13], atomic-orbital closecoupling (AOCC) approaches [14][15][16][17][18][19][20][21][22][23][24] and methods based on direct solution of the time-dependent Schrödinger equation (TDSE) [10,[25][26][27][28].…”