Frenetic aspects of second order response

TL;DR

This paper explores the frenetic contributions to second order response in statistical systems near equilibrium, highlighting how dynamical activity influences nonlinear responses across various physical examples.

Contribution

It introduces the concept of frenetic contributions in second order response and illustrates their role in diverse physical phenomena near thermal equilibrium.

Findings

Frenetic contributions affect nonlinear response in physical systems.

Dynamical activity changes are observable only through nonlinear response.

Examples include dielectric response and nonlinear Sutherland--Einstein relation.

Abstract

Starting from second order around thermal equilibrium, the response of a statistical mechanical system to an external stimulus is not only governed by dissipation and depends explicitly on dynamical details of the system. The so called frenetic contribution in second order around equilibrium is illustrated in different physical examples, such as for non-thermodynamic aspects in the coupling between system and reservoir, for the dependence on disorder in dielectric response and for the nonlinear correction to the Sutherland--Einstein relation. More generally, the way in which a system's dynamical activity changes by the pertubation is visible (only) from nonlinear response.