dc.contributor.author Duke, Jessica Ryan dc.date.accessioned 2017-07-07T12:48:46Z dc.date.available 2017-07-07T12:48:46Z dc.date.issued 2017-05-30 dc.identifier.other Duke_cornellgrad_0058F_10292 dc.identifier.other http://dissertations.umi.com/cornellgrad:10292 dc.identifier.other bibid: 9948878 dc.identifier.uri https://hdl.handle.net/1813/51655 dc.description.abstract Understanding the mechanisms and timescales of charge and energy transfer processes in large, complex molecular systems is an essential step towards the rational design of a wide variety of renewable energy technologies. Unfortunately, the quantum mechanical nature of these reactions, where nuclear motions mediate transitions between electronic states, makes them infeasible to simulate exactly in many-body systems because of the scaling limitations of exact quantum dynamics methods. Developing approximate quantum dynamics methods capable of efficiently, yet accurately describing quantum processes in high-dimensional systems is, therefore, an ongoing effort in the field of theoretical chemistry and the focus of this dissertation. The two methods we discuss here are based on the imaginary-time path integral formulation of the quantum Boltzmann distribution that allows quantum degrees of freedom to be represented by classical ring polymers" in an extended phase space. Specifically, these methods are versions of the promising ring polymer molecular dynamics (RPMD) method for approximating quantum real-time thermal correlation functions using classical ring polymer trajectories. The first method we discuss, mean field (MF)-RPMD, extends the original RPMD formulation to multi-electron systems and describes nuclear dynamics on an average potential energy surface. We show how a novel implementation of this method for rate calculations yields accurate electron transfer rate constants across a wide range of parameter regimes. The second method we describe, mapping variable (MV)-RPMD, captures electronic state transitions using only classical MD trajectories by employing an exact mapping from discrete electronic states to classical phase-space variables. In order to use this method to study photochemistry, we derive a function in the MV-RPMD framework that reports on electronic state populations as a function of time, and we introduce a constraint protocol to initialize an MV-RPMD simulation to a particular electronic state. We numerically demonstrate the accuracy of this population function and constraint technique in the context of model systems undergoing electronic state transmission/reflection and photodissociation. dc.language.iso en_US dc.subject Simulation dc.subject Chemistry dc.subject path integrals dc.subject photochemistry dc.subject quantum dynamics dc.subject ring polymer molecular dynamics dc.title Path Integral Dynamics Methods for Simulating Quantum Processes in Multi-Electron, Condensed-Phase Systems dc.type dissertation or thesis thesis.degree.discipline Chemistry and Chemical Biology thesis.degree.grantor Cornell University thesis.degree.level Doctor of Philosophy thesis.degree.name Ph. D., Chemistry and Chemical Biology dc.contributor.chair Ananth, Nandini dc.contributor.committeeMember Ezra, Gregory S dc.contributor.committeeMember Marohn, John A dcterms.license https://hdl.handle.net/1813/59810 dc.identifier.doi https://doi.org/10.7298/X4G44NDR
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