CSDS seminar – Ensemble averages using nonlinear response relations – Manuel Santos Gutierrez

Abstract: Computing ensemble averages is a fundamental procedure in the statistical analysis of dynamical models. When an external field is applied to the system of interest, its response is determined by the average of many individual ensemble members evolving in the forced scenario. The quality of this averaging procedure, however, heavily depends on the nature of the underlying system. The transient time correlation function (TTCF) method is widely used in molecular fluids to compute non-equilibrium transport properties, providing improved signal-to-noise ratios in ensemble averages without requiring prohibitively large sample sizes. In spite of its success in molecular and turbulent fluid systems, the method has not been systematically explored for more general non-equilibrium dynamical systems, including geophysical applications where the invariant measure is typically unknown. In this work, we present an analytical and numerical investigation of the TTCF method for computing nonlinear response functions in systems far from equilibrium.