Snap, Crackle, and Pop: This is why the potential of mean force clashes with the fluctuation dissipation relation

Abstract

We analyze the non-linear generalized Langevin equation which contains a thermodynamic force. We show that even for systems in thermal equilibrium the presence of the thermodynamic force implies that the auto-correlation function of the fluctuating force becomes non-stationary. We further illustrate that a standard coarse-graining procedure that neglects this fact predicts waiting-time distributions incompatible with the original, microscopic process. We conclude that one needs to proceed with care when adding thermodynamic driving forces to the Langevin equation.

6 pages, 3 figures

References in corpus (3)

• Classical dynamical density functional theory: from fundamentals to applications
• Time-dependent friction effects on vibrational infrared frequencies and line shapes of liquid water
• On the generalized Langevin equation and the Mori projection operator technique