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

Abstract

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 properties of absorbing potentials in order to calculate the flux operator matrix elements. We show the necessity of introducing the appropriate Hankel–Riccati functions when the full Hamiltonian contains a centrifugal term in 1/R2 in order to reduce the computational time. The collisional system Si4++He is studied as a test case.