  The complex physics of glass forming systems is controlled by the structure
of the low energy portions of their potential energy landscapes. Here, we
report that a modified metadynamics algorithm efficiently explores and samples
low energy regions of such high-dimensional landscapes. In the energy landscape
for a model foam, our algorithm finds and descends meandering `canyons' in the
landscape, which contain dense clusters of energy minima along their floors.
Similar canyon structures in the energy landscapes of two model glass formers
-- hard sphere fluids and the Kob-Andersen glass -- allow us to reach high
densities and low energies, respectively. In the hard sphere system, fluid
configurations are found to form continuous regions that cover the canyon
floors up to densities well above the jamming transition. For the Kob-Andersen
glass former, our technique samples low energy states with modest computational
effort, with the lowest energies found approaching the predicted Kauzmann
limit.
