A Computational and Theoretical Study of Conductance in Hydrogen-bonded Molecular Junctions

A Computational and Theoretical Study of Conductance in Hydrogen-bonded Molecular Junctions PDF Author: Michael Wimmer
Publisher:
ISBN:
Category : Charge exchange
Languages : en
Pages : 125

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Book Description
This thesis is devoted to the theoretical and computational study of electron transport in molecular junctions where one or more hydrogen bonds are involved in the process. While electron transport through covalent bonds has been extensively studied, in recent work the focus has been shifted towards hydrogen-bonded systems due to their ubiquitous presence in biological systems and their potential in forming nano- junctions between molecular electronic devices and biological systems. This analysis allows us to significantly expand our comprehension of the experimentally observed result that the inclusion of hydrogen bonding in a molecular junction significantly impacts its transport properties, a fact that has important implications for our understanding of transport through DNA, and nano-biological interfaces in general. In part of this work I have explored the implications of quasiresonant transport in short chains of weakly-bonded molecular junctions involving hydrogen bonds. I used theoretical and computational analysis to interpret recent experiments and explain the role of Fano resonances in the transmission properties of the junction.In a different direction, I have undertaken the study of the transversal conduction through nucleotide chains that involve a variable number of different hydrogen bonds, e.g. NH...O, OH...O, and NH...N, which are the three most prevalent hydrogen bonds in biological systems and organic electronics. My effort here has fo- cused on the analysis of electronic descriptors that allow a simplified conceptual and computational understanding of transport properties. Specifically, I have expanded our previous work where the molecular polarizability was used as a conductance de- scriptor to include the possibility of atomic and bond partitions of the molecular polarizability. This is important because it affords an alternative molecular descrip- tion of conductance that is not based on the conventional view of molecular orbitals as transport channels. My findings suggest that the hydrogen-bond networks are crucial in understanding the conductance of these junctions. A broader impact of this work pertains the fact that characterizing transport through hydrogen bonding networks may help in developing faster and cost-effective approaches to personalized medicine, to advance DNA sequencing and implantable electronics, and to progress in the design and application of new drugs.

A Computational and Theoretical Study of Conductance in Hydrogen-bonded Molecular Junctions

A Computational and Theoretical Study of Conductance in Hydrogen-bonded Molecular Junctions PDF Author: Michael Wimmer
Publisher:
ISBN:
Category : Charge exchange
Languages : en
Pages : 125

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Book Description
This thesis is devoted to the theoretical and computational study of electron transport in molecular junctions where one or more hydrogen bonds are involved in the process. While electron transport through covalent bonds has been extensively studied, in recent work the focus has been shifted towards hydrogen-bonded systems due to their ubiquitous presence in biological systems and their potential in forming nano- junctions between molecular electronic devices and biological systems. This analysis allows us to significantly expand our comprehension of the experimentally observed result that the inclusion of hydrogen bonding in a molecular junction significantly impacts its transport properties, a fact that has important implications for our understanding of transport through DNA, and nano-biological interfaces in general. In part of this work I have explored the implications of quasiresonant transport in short chains of weakly-bonded molecular junctions involving hydrogen bonds. I used theoretical and computational analysis to interpret recent experiments and explain the role of Fano resonances in the transmission properties of the junction.In a different direction, I have undertaken the study of the transversal conduction through nucleotide chains that involve a variable number of different hydrogen bonds, e.g. NH...O, OH...O, and NH...N, which are the three most prevalent hydrogen bonds in biological systems and organic electronics. My effort here has fo- cused on the analysis of electronic descriptors that allow a simplified conceptual and computational understanding of transport properties. Specifically, I have expanded our previous work where the molecular polarizability was used as a conductance de- scriptor to include the possibility of atomic and bond partitions of the molecular polarizability. This is important because it affords an alternative molecular descrip- tion of conductance that is not based on the conventional view of molecular orbitals as transport channels. My findings suggest that the hydrogen-bond networks are crucial in understanding the conductance of these junctions. A broader impact of this work pertains the fact that characterizing transport through hydrogen bonding networks may help in developing faster and cost-effective approaches to personalized medicine, to advance DNA sequencing and implantable electronics, and to progress in the design and application of new drugs.

Theoretical Treatments of Hydrogen Bonding

Theoretical Treatments of Hydrogen Bonding PDF Author: Dušan Hadži
Publisher: John Wiley & Sons
ISBN:
Category : Science
Languages : en
Pages : 344

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Book Description
Hydrogen bonding is crucial in many chemical and biochemical reactions, as well as in determining material properties. A good insight into the theoretical methods of treating hydrogen bonding is essential for those wishing to model its effects computationally in a wide range of fields involving hydrogen bonding, as well as those wishing to extract the maximal amount of information from experimental data. Theoretical Treatments of Hydrogen Bonding presents the reader with the state of the art of the key theoretical approaches to hydrogen bonding and considers the hydrogen bond from the various aspects. The first five chapters are devoted to the methods used for treating the electronic basis of hydrogen bonding, including a consideration of the electrostatic model, density functional theory and molecular orbital methods. Later chapters consider the dynamics of hydrogen bonds with particular attention to the treatment of proton transfer; manifestations of dynamics as reflected in infrared spectra and nuclear magnetic relaxation are also considered. Hydrogen bonding in liquids and solids such as ferroelectrics are included. The book concludes with an epilogue which discusses the likely development of hydrogen bond computations in very large chemical systems. Theoretical Treatments of Hydrogen Bonding offers the reader a comprehensive view of the current theoretical approaches to hydrogen bonding. It is a valuable presentation of theoretical tools useful to those looking for the most appropriate approach for treating a particular problem involving hydrogen bonding.

Hydrogen Bonding

Hydrogen Bonding PDF Author: Steve Scheiner
Publisher: Oxford University Press
ISBN: 0198025092
Category : Science
Languages : en
Pages : 396

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Book Description
Because of the importance of the hydrogen bond, there have been scores of insights gained about its fundamental nature by quantum chemical computations over the years. Such methods can probe subtle characteristics of the electronic structure and examine regions of the potential energy surface that are simply not accessible by experimental means. The maturation of the techniques, codes, and computer hardware have permitted calculations of unprecedented reliability and rivaling the accuracy of experimental data. This book strives first toward an appreciation of the power of quantum chemistry to analyze the deepest roots of the hydrogen bond phenomenon. It offers a systematic and understandable account of decades of such calculations, focusing on the most important findings. This book provides readers with the tools to understand the original literature, and to perhaps carry out some calculations of their very own on systems of interest.

Hydrogen Bonding - New Insights

Hydrogen Bonding - New Insights PDF Author: Slawomir Grabowski
Publisher: Springer
ISBN: 9789048172122
Category : Science
Languages : en
Pages : 0

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Book Description
This book uses examples from experimental studies to illustrate theoretical investigations, allowing greater understanding of hydrogen bonding phenomena. The most important topics in recent studies are covered. This volume is an invaluable resource that will be of particular interest to physical and theoretical chemists, spectroscopists, crystallographers and those involved with chemical physics.

Understanding Hydrogen Bonds

Understanding Hydrogen Bonds PDF Author: Slawomir J Grabowski
Publisher:
ISBN: 9781788014793
Category : Science
Languages : en
Pages : 450

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Book Description
The area of hydrogen bonding is one that is well studied but our understanding continues to develop as the power of both computational and experimental techniques has improved. This book presents an up-to-date overview of our theoretical and experimental understanding of the hydrogen bond. It covers both well-established and novel approaches, new types of interaction that might be classified as hydrogen bonds and a comparison of hydrogen bonds to other types of non-covalent interactions.

Single-Molecule Electronics

Single-Molecule Electronics PDF Author: Manabu Kiguchi
Publisher: Springer
ISBN: 9811007241
Category : Science
Languages : en
Pages : 239

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Book Description
This book presents a multidisciplinary approach to single-molecule electronics. It includes a complete overview of the field, from the synthesis and design of molecular candidates to the prevalent experimental techniques, complemented by a detailed theoretical description. This all-inclusive strategy provides the reader with the much-needed perspective to fully understand the far-reaching ramifications of single-molecule electronics. In addition, a number of state-of-the-art topics are discussed, including single-molecule spectro-electrical methods, electrochemical DNA sequencing technology, and single-molecule chemical reactions. As a result of this integrative effort, this publication may be used as an introductory textbook to both graduate and advanced undergraduate students, as well as researchers with interests in single-molecule electronics, organic electronics, surface science, and nanoscience.

Conductance States of Molecular Junctions for Encoding Binary Information

Conductance States of Molecular Junctions for Encoding Binary Information PDF Author: Luis Alberto Agapito
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Electronic devices, for logical and memory applications, are constructed based on bistable electronic units that can store binary information. Molecular electronics proposes the use of single molecules--with two distinctive states of conductance--as bistable units that can be used to create more complex electronic devices. The conductance of a molecule is strongly influenced by the contacts used to address it. The purpose of this work is to determine the electrical characteristics of several candidate molecular junctions, which are composed of a molecule and contacts. Specifically, we are interested in determining whether binary information, "0" or "1," can be encoded in the low- and high-conductance states of the molecular junctions. First, we calculate quantum-mechanically the electronic structure of the molecular junction. Second, the continuous electronic states of the contacts, originated from their infinite nature, are obtained by solving the Schrodinger equation with periodic boundary conditions. Last, the electron transport through the molecular junctions is calculated based on a chemical interpretation of the Landauer formalism for coherent transport, which involves the information obtained from the molecule and the contacts. Metal-molecule-metal and metal-molecule-semiconductor junctions are considered. The molecule used is an olygo(phenylene ethynylene) composed of three benzene rings and a nitro group in the middle ring; this molecule is referred hereafter as the nitroOPE molecule. Gold, silicon, and metallic carbon nanotubes are used as contacts to the molecule. Results from the calculations show that the molecular junctions have distinctive states of conductance for different conformational and charge states. High conductance is found in the conformation in which all the benzene rings of the nitroOPE are coplanar. If the middle benzene ring is made perpendicular to the others, low conductance is found. Also, the negatively charged junctions (anion, dianion) show low conductance. Whenever a semiconducting contact is used, a flat region of zero current is found at low bias voltages. The results indicate that the use of Si contacts is possible; however, because of the flat region, the operating point of the devices needs to be moved to higher voltages.

Computational Methods for Large Systems

Computational Methods for Large Systems PDF Author: Jeffrey R. Reimers
Publisher: John Wiley & Sons
ISBN: 0470934727
Category : Science
Languages : en
Pages : 568

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Book Description
While its results normally complement the information obtained by chemical experiments, computer computations can in some cases predict unobserved chemical phenomena Electronic-Structure Computational Methods for Large Systems gives readers a simple description of modern electronic-structure techniques. It shows what techniques are pertinent for particular problems in biotechnology and nanotechnology and provides a balanced treatment of topics that teach strengths and weaknesses, appropriate and inappropriate methods. It’s a book that will enhance the your calculating confidence and improve your ability to predict new effects and solve new problems.

Molecular Electronics

Molecular Electronics PDF Author: Juan Carlos Cuevas
Publisher: World Scientific
ISBN: 9814282588
Category : Science
Languages : en
Pages : 724

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Book Description
This book provides a comprehensive overview of the rapidly developing field of molecular electronics. It focuses on our present understanding of the electrical conduction in single-molecule circuits and provides a thorough introduction to the experimental techniques and theoretical concepts. It will also constitute as the first textbook-like introduction to both the experiment and theory of electronic transport through single atoms and molecules. In this sense, this publication will prove invaluable to both researchers and students interested in the field of nanoelectronics and nanoscience in general. Molecular Electronics is self-contained and unified in its presentation. It may be used as a textbook on nanoelectronics by graduate students and advanced undergraduates studying physics and chemistry. In addition, included are previously unpublished material that will help researchers gain a deeper understanding into the basic concepts involved in the field of molecular electronics.

Unimolecular and Supramolecular Electronics II

Unimolecular and Supramolecular Electronics II PDF Author: Robert M. Metzger
Publisher: Springer Science & Business Media
ISBN: 364227398X
Category : Science
Languages : en
Pages : 283

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Book Description
Molecular Electronic Junction Transport: Some Pathways and Some Ideas, by Gemma C. Solomon, Carmen Herrmann and Mark A. Ratner Unimolecular Electronic Devices, by Robert M. Metzger and Daniell L. Mattern Active and Non-Active Large-Area Metal–Molecules–Metal Junctions, by Barbara Branchi, Felice C. Simeone and Maria A. Rampi Charge Transport in Single Molecular Junctions at the Solid/Liquid Interface, by Chen Li, Artem Mishchenko and Thomas Wandlowski Tunneling Spectroscopy of Organic Monolayers and Single Molecules, by K. W. Hipps Single Molecule Logical Devices, by Nicolas Renaud, Mohamed Hliwa and Christian Joachim