Upon excitation of Cl-(H2O)(3) and I-(H2O)(3) clusters, the electron transfers from the anionic precursor to the solvent, and then the excess electron is stabilized by polar solvent molecules. This process has been investigated using ab initio molecular dynamics (AIMD) simulations of excited states of Cl-(H2O)(3) and I-(H2O)(3) clusters. The AIMD simulation results of Cl-(H2O)(3) and I-(H2O)(3) are compared, and they are found to be similar. Because the role of the halogen atom in the photoexcitation mechanism is controversial, we also carried out AIMD simulations for the ground-state bare excess electron-water trimer [e(-)(H2O)(3)] at 300 K, the results of which are similar to those for the excited state of X-(H2O)(3) with zero kinetic energy at the initial excitation. This indicates that the rearrangement of the complex is closely related to that of e(-)(H2O)(3), whereas the role of the halide anion is not as important.