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.