  The dynamics of an F--center created by an oxygen vacancy on the
$\mathrm{TiO_{2}(110)}$ rutile surface has been investigated using {\it ab
initio} molecular dynamics. These simulations uncover a truly complex,
time-dependent behavior of fluctuating electron localization topologies in the
vicinity of the oxygen vacancy. Although the two excess electrons are found to
populate preferentially the second subsurface layer, they occasionally visit
surface sites and also the third subsurface layer. This dynamical behavior of
the excess charge explains hitherto conflicting interpretations of both
theoretical findings and experimental data.
