Nonlinear coupling and relaxation of fluctuations and the central peak

Abstract

A simple model Hamiltonian for a structural phase transition is discussed. It is shown that using the modecular field approximation one obtains a nonlinear coupling of the order parameter and entropy fluctuations. This results in a central peak in the order parameter fluctuation spectrum. The width of the central peak is proportional to the entropy relaxation rate. © 1973.