Nandini Ananth

Professor Nandini Ananth, Cornell University.  "Path Integral Methods for Simulating Nonadiabatic Charge and Energy Transfer Dynamics."  Theoretical Chemistry Lecture.

Abstract:  Simulating inherently quantum mechanical charge and energy transfer processes in the condensed phase remains an outstanding challenge to theory. The high computational costs associated with exact quantum dynamic simulations of large systems necessitate the development of approximate methods that (i) exhibit low computational cost and near-linear scaling with system dimensionality; (ii) capture important quantum effects including tunneling, zero-point energy, and coherence effects; and (iii) employ a consistent framework to describe transitions between electronic states and the dynamics of nuclei to accurately capture nonadiabatic processes. In this talk, we will discuss several well-established, approximate methods derived from the real- time and imaginary-time path integral formulations of quantum mechanics. We will explore their regimes of applicability based on the criteria outlined above. We then introduce a novel method developed by our group for the direct dynamic simulation of photo-induced chemical reactions in the condensed phase, Mapping-Variable Ring Polymer Molecular Dynamics (MV-RPMD). Finally, we will numerically demonstrate the accuracy and applicability of this method in simulations of photo-induced excited electronic state dynamics.