Wave packet methods for charge exchange processes in ion-atom collisions

The efficiency of different time-independent and time-dependent wave packet methods to calculate charge-exchange cross sections is discussed. The time -independent spectral projection method is based on the Chebyshev expansion of the resolvent function and represents an interesting alternative to the usual Fourier method which involves a time propagation. On the other hand, the flux operator method still requires propagation in time but uses the p roperties of absorbing potentials in order to calculate the flux operator m atrix elements. We show the necessity of introducing the appropriate Hankel -Riccati functions when the full Hamiltonian contains a centrifugal term in 1/R-2 in order to reduce the computational time. The collisional system Si 4+ + He is studied as a test case. (C) 2001 American Institute of Physics.