Fluctuating phases and fluctuating relaxation times in glass forming liquids

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© 2019 Author(s). The presence of fluctuating local relaxation times, τr→(t) has been used for some time as a conceptual tool to describe dynamical heterogeneities in glass-forming systems. However, until now no general method is known to extract the full space and time dependent τr→(t) from experimental or numerical data. Here we report on a new method for determining a local phase field, θr→(t) tdt′τr→(t′) from snapshots {r→(ti)}i=1...M of the positions of the particles in a system, and we apply it to extract θr→(t) and τr→(t) from numerical simulations. By studying how this phase field depends on the number of snapshots, we find that it is a well defined quantity. By studying fluctuations of the phase field, we find that they describe heterogeneities well at long distance scales.