Quantum dynamics of many-atom systems by the classically based separable potential (CSP) method: Calculations for l^-(Ar)₁₂ in full dimensionality

A recently developed method for time-dependent quantum simulations of large systems on short time scales is applied to the dynamics following electron photodetachment from the clusters I^- (Ar)₂ and I ^-(Ar)₁₂. The problem is treated in full dimensionality, incorporating all vibrational degrees of freedom, by the classically based separable potential (CSP) approach. This is essentially an approximate time-dependent quantization of classical dynamics: Classical molecular dynamics is used to generate effective, single mode separable time-dependent potentials for each degree of freedom. The quantum dynamics is then propagated separately for each mode, using the effective potentials that implicitly include effects such as energy transfer between the modes. In the current application of the CSP method we calculate properties relevant for the interpretation of spectroscopies, such as correlation functions of wave packets, as well as time-dependent atom-atom distribution functions, pertinent to future diffraction experiments using ultrafast pulses. The insight obtained from the quantum dynamics of these clusters is discussed. In particular, light is thrown on the differences in the dynamics associated with the system landing on the three different electronic surfaces of the neutral 1(²P)-(Ar)_n system.