  The dynamics of a polydisperse model glassformer are investigated by
augmenting molecular dynamics (MD) simulation with swap Monte Carlo (SMC).
Three variants of the SMC algorithm are analyzed with regard to convergence and
performance. We elucidate the microscopic mechanism responsible for the drastic
speed-up of structural relaxation at low temperature. It manifests in a
stepwise increase of the mean squared displacement when the time scale between
the application of swap sweeps is significantly larger than a characteristic
microscopic time scale. Compared to Newtonian dynamics, with the hybrid MD-SMC
dynamics the glass transition shifts to a lower temperature and a different
temperature dependence of the localization length is found.
