Cross-correlations in the fluctuation–dissipation relation influence barrier-crossing dynamics

The Generalized Langevin Equation has been successfully used to model and understand the conformational dynamics of molecules in solution. However, recent works have demonstrated that, in these kinds of applications, the usual fluctuation-dissipation relation connecting the statistics of the random force to the memory kernel could contain a cross-correlation term. In this work, we systematically explore the origins of this cross-correlation term and argue that it plays a role, particularly in the folding dynamics of biopolymers. Finally, we propose an approximation for the cross-correlation term within the usual fluctuation-dissipation relation.