Electronic wave packet motion in water dimer cation: A many electron description

The time evolution of a non-stationary electronic wave packet created by a sudden ionization is computed using a multi-reference time-dependent approach at a frozen geometry of the nuclei. The methodology is illustrated for the water dimer cation. The electron density as well as the dipole moment are computed as a function of time and used as a probe for the charge migration following upon the sudden removal of a valence electron. It is shown that there is significant purely electronic dynamics on a few femtosecond time scale and that the characteristics of the charge motion depend of the degree of localization of the initial hole formed in the impulsive ionization process. (C) 2009 Elsevier B.V. All rights reserved.