  The simulation of rare events is one of the key problems in atomistic
simulations. Towards its solution a plethora of methods have been proposed.
Here we combine two such methods metadynamics and inte-grated tempering
sampling. In metadynamics the fluctuations of a carefully chosen collective
variable are amplified, while in integrated tempering sampling the system is
pushed to visit an approximately uniform interval of energies and allows
exploring a range of temperatures in a single run. We describe our ap-proach
and apply it to the two prototypical systems a SN2 chemical reaction and to the
freezing of silica. The combination of metadynamics and integrated tempering
sampling leads to a powerful method. In par-ticular in the case of silica we
have measured more than one order of magnitude acceleration.
