Dynamic Order-Disorder in Atomistic Models of Structural Glass Formers

Abstract

The glass transition is the freezing of a liquid into a solid state without evident structural order. Although glassy materials are well characterized experimentally, the existence of a phase transition into the glass state remains controversial. Here, we present numerical evidence for the existence of a novel first-order dynamical phase transition in atomistic models of structural glass formers. In contrast to equilibrium phase transitions, which occur in configuration space, this transition occurs in trajectory space, and it is controlled by variables that drive the system out of equilibrium. Coexistence is established between an ergodic phase with finite relaxation time and a nonergodic phase of immobile molecular configurations. Thus, we connect the glass transition to a true phase transition, offering the possibility of a unified picture of glassy phenomena.

Fluctuation analysis of time-averaged mean-square displacement for the Langevin equation with time-dependent and fluctuating diffusivity

“…In particular, the comparison of the crossover time determined from the RSD of the TAMSD with other characteristic times (such as the α-relaxation time) will be interesting. Garrahan, Chandler and coworkers [44][45][46] analyzed so-called the "activity" to study the dynamics of supercooled liquids. The activity is defined as:…”

Steered transition path sampling

“…This could be useful for mechanisms with many intermediates, such as isomerizations in materials and certain biomolecular systems. By the same token, we expect the method to outperform shooting in enhancing or suppressing mobility in models of glassy dynamics, where it can be necessary to have a coincidence of facilitating features 26,27 ; it would be interesting to compare the method with alternative path sampling schemes in which successive paths are correlated by construction 33 .…”

“…In particular, the method allows accumulation of rare numbers of events that are individually common for control of currents in a space of order parameters, as previously sampled by TPS 26,27 and methods for calculating large deviation functions 28,29 . The fact that all integration is forward in time allows treatment of microscopically irreversible systems and the study of relaxation from arbitrary initial conditions.…”

Thermodynamic formalism for dissipative quantum walks

“…1, suggests that the topology of the underlying graph can be responsible for the occurrence of different dynamical phases. In particular, exploring more complex graph structures, one could characterize the cases where the transition is sharp (as found in other physical contexts [31][32][33]), which would imply a dynamical phase transition between effectively classical and quantum coherent regimes.…”

“…The large deviation approach is the mathematical framework allowing us to access this extra information [24]. In fact, recently, its application to classical and quantum nonequilibrium dynamics has being crucial to show the presence of dynamical phase transitions and dynamical crossover phenomena [31][32][33]. In particular, as first observed in [32], the quantum jump approach provides a quantum stochastic process that is well suited to be analysed with the LD theory.…”