  We present a microscopic picture of silver dynamics in GeSe$_{3}$:Ag glass
obtained from {\it ab initio} simulation. The dynamics of Ag is explored at two
temperatures, 300K and 700K. In the relaxed network, Ag occupies bond centers
between suitably separated host sites. At 700K, Ag motion proceeds via a
trapping-release dynamics, between "super traps" or cages consisting of
multiple bond-center sites in a small volume. Our work offers a first
principles identification of trapping centers invoked in current theories, with
a description of their properties. We compute the charge state of the Ag in the
network, and show that it is neutral if weakly bonded and Ag$^+$ if in a
trapping center.
