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Frontiers in the Atomistic Modeling ...

Li, Zhi.

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Frontiers in the Atomistic Modeling of Molecular Junctions: Bringing Theory Closer to Experiment.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Frontiers in the Atomistic Modeling of Molecular Junctions: Bringing Theory Closer to Experiment./
Author:	Li, Zhi.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2019,
Description:	188 p.
Notes:	Source: Dissertations Abstracts International, Volume: 81-04, Section: B.
Contained By:	Dissertations Abstracts International81-04B.
Subject:	Molecular chemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=13881140
ISBN:	9781085784047

Frontiers in the Atomistic Modeling of Molecular Junctions: Bringing Theory Closer to Experiment.
Li, Zhi.

Frontiers in the Atomistic Modeling of Molecular Junctions: Bringing Theory Closer to Experiment. - Ann Arbor : ProQuest Dissertations & Theses, 2019 - 188 p.

Source: Dissertations Abstracts International, Volume: 81-04, Section: B.

Thesis (Ph.D.)--University of Rochester, 2019.

This item must not be sold to any third party vendors.

This thesis focuses on advancing the theory and simulation needed to atomistically understand molecular junction experiments where a single molecule acts as a bridge between two metal electrodes. In this class of experiments, a molecular junction is mechanically elongated while measuring its conductance, or its conductance and the applied force. The interest in this class of experiments is that they provide a versatile platform to investigate chemistry and physics at the nanoscale. To atomistically understand experiments and guide experimental progress, in this thesis we introduce new simulation tools and strategies that establish a contact between theory and experiment. We use such those technical advances to provide atomistic understanding of key experiments in the area, and to propose new frontiers for future experimental progress. In particular, we developed a non-reactive classical force field that accurately captures metal-molecule interactions. Such force field opens the possibility to perform classical molecular dynamics simulations of molecules on surfaces on experimentally relevant system size and time scales. Using it, we developed atomistic understanding of two state-of-the-art low temperature scanning tunneling microscopy (STM) experiments that measure the conductance of a single molecular wire (composed of polyfluorenes or graphene nanoribbons) as a continuous function of its length. Then we turned our attention to the problem of how to compare theory and experiments in STM break junction (STM-BJ) experiments where the conductance is measured on thousands of freshly formed molecular junctions to generate a reproducible conductance histogram. For this, we introduced a modeling strategy to model the STM-BJ experiments with statistics that takes into account uncertainties in junction geometries in and between experiments. Using such a strategy, we computationally examined possible contributing factors to the wide conductance dispersion encountered in the experiments and developed an atomistic understanding of the key effects. Last, we computationally proposed a new route -- the mechanical route -- to tune the degree of quantum coherence in transport of molecular junctions.

ISBN: 9781085784047Subjects--Topical Terms:

1071612
Molecular chemistry.

Frontiers in the Atomistic Modeling of Molecular Junctions: Bringing Theory Closer to Experiment.
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520 $a This thesis focuses on advancing the theory and simulation needed to atomistically understand molecular junction experiments where a single molecule acts as a bridge between two metal electrodes. In this class of experiments, a molecular junction is mechanically elongated while measuring its conductance, or its conductance and the applied force. The interest in this class of experiments is that they provide a versatile platform to investigate chemistry and physics at the nanoscale. To atomistically understand experiments and guide experimental progress, in this thesis we introduce new simulation tools and strategies that establish a contact between theory and experiment. We use such those technical advances to provide atomistic understanding of key experiments in the area, and to propose new frontiers for future experimental progress. In particular, we developed a non-reactive classical force field that accurately captures metal-molecule interactions. Such force field opens the possibility to perform classical molecular dynamics simulations of molecules on surfaces on experimentally relevant system size and time scales. Using it, we developed atomistic understanding of two state-of-the-art low temperature scanning tunneling microscopy (STM) experiments that measure the conductance of a single molecular wire (composed of polyfluorenes or graphene nanoribbons) as a continuous function of its length. Then we turned our attention to the problem of how to compare theory and experiments in STM break junction (STM-BJ) experiments where the conductance is measured on thousands of freshly formed molecular junctions to generate a reproducible conductance histogram. For this, we introduced a modeling strategy to model the STM-BJ experiments with statistics that takes into account uncertainties in junction geometries in and between experiments. Using such a strategy, we computationally examined possible contributing factors to the wide conductance dispersion encountered in the experiments and developed an atomistic understanding of the key effects. Last, we computationally proposed a new route -- the mechanical route -- to tune the degree of quantum coherence in transport of molecular junctions.
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