Generalized Brownian motion: thermodynamic force and potential; thermodynamic equilibrium susceptibility (section 2.3)
Equilibrium
statistical thermodynamics in the presence of a perturbing field;
another equation for static susceptibility (first part of section 2.4)
Linear
response and fluctuation
dissipation relations: non equilibrium averages in the case of
instantaneous switch off of a constant perturbation (section 2.4.1 first
part)
Reference book: "Non equilibrium statistical physics: a modern perspective" by Livi and Politi