Mode-coupling theory

Mode-coupling theory is a microscopic framework for glass formation in which density fluctuations feed back on their own dynamics, producing increasingly slow relaxation.

Intermediate scattering function: A time-dependent correlation function measuring how density fluctuations at a chosen wave number persist in a material. Mode-coupling theory predicts its characteristic decay and plateau as a liquid approaches glass formation.
Dynamic light scattering: An experimental method that measures fluctuations in scattered light to determine the dynamics of particles or density variations. It tests the slow correlation decay that mode-coupling theory predicts.
Walter Götze: A German theoretical physicist whose work established and developed mode-coupling theory for glass-forming liquids. His derivations and synthesis shaped the theory's standard formulation.
Random first-order transition theory: A theoretical framework that describes glass formation through an underlying thermodynamic transition and mosaic-like states. It attributes glassy slowdown to a different mechanism than mode-coupling feedback.
Nonergodicity parameter: The long-time limit of a correlation function, indicating whether a system retains memory of its initial state. Its nonzero value marks the idealized dynamical arrest predicted by the theory.
Static structure factor: A measure of spatial density correlations in a material as a function of wave number. It supplies structural input to standard mode-coupling equations.
Uli Bengtzelius: A Swedish physicist who co-developed an early microscopic mode-coupling account of the glass transition. His collaboration helped introduce the theory's central density-feedback approach.
Activated dynamics: Relaxation through thermally enabled barrier crossing between metastable configurations. Such processes restore relaxation below the ideal transition where standard mode-coupling predicts arrest.
Memory function: A time-dependent term in an equation of motion that represents the influence of a system's past on its present dynamics. The theory builds a nonlinear memory kernel from coupled density correlations.
Density fluctuation: A local deviation of particle density from its average value. These are the microscopic variables whose nonlinear coupling drives the theory's feedback.

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Glassy systemsRelated: It offers a kinetic account of slowdown distinct from explanations based on an ideal thermodynamic transition.