A Gentle Introduction to Nanotechnology and Nanoscience
13 Feb 2006 | Online Presentations | Contributor(s): Mark A. Ratner
While the Greek root nano just means dwarf, the nanoscale has become a giant focus of contemporary science and technology. We will examine the fundamental issues underlying the excitement involved in nanoscale research - what, why and how. Specific topics include assembly, properties, applications, and societal issues.
DNA Charge Motion: Regimes and Behaviors
28 Jul 2005 | Online Presentations | Contributor(s): Mark A. Ratner
Because DNA is a quasi-one-dimensional species, and
because each base is a pi-type chromphore, it was long ago suggested that DNA could conduct electricity. This has become a widely investigated area, and remains of interest for fundamental science and for applications. We will discuss a very simple picture involving a combination of hopping and tunneling that seems to fit much of the available data. Other aspects, including the distance-dependent reorganization energy, defect energetics, hopping
models with strange distance dependences, and fabrication into
quantum-dot detection entities, will also be discussed.
Energy and Nanoscience A More Perfect Union
29 Mar 2009 | Online Presentations | Contributor(s): Mark A. Ratner
Huge problems of energy and sustainability confront the science/engineering community, mankind, and our planet. The energy problem comes in many dimensions, including supply, demand, conservation, transportation, and storage. This overview will stress the nature of these problems, and offer a few areas where theoretical chemistry can make substantial contributions to solving them. Also discussed are excitons in solar cells and on advanced batteries.
Mark Ratner Interview on Nanotechnology
23 Mar 2006 | Online Presentations | Contributor(s): Mark A. Ratner, Krishna Madhavan
Nanotechnology interview with Krishna Madhavan.
MCW07 Modeling Charging-based Switching in Molecular Transport Junctions
23 Aug 2007 | Online Presentations | Contributor(s): Sina Yeganeh, Misha Galperin, Mark A. Ratner
We will discuss several proposed explanations for the switching and negative differential resistance behavior seen in some molecular junctions. It is shown that a proposed polaron model is successful in predicting both hysteresis and NDR behavior, and the model is elaborated with image charge effects and parameters from electronic structure calculations. This model includes the effects of conformational change, charging, and image charge stabilization.
Sina Yeganeh is a graduate student ...
MCW07 Simple Models for Molecular Transport Junctions
13 Sep 2007 | Online Presentations | Contributor(s): Misha Galperin, Abraham Nitzan, Mark A. Ratner
We review our recent research on role of interactions in molecular transport junctions. We consider simple models within nonequilibrium Green function approach (NEGF) in steady-state regime.
Molecular Transport Structures: Elastic Scattering, Vibronic Effects and Beyond
13 Feb 2006 | Online Presentations | Contributor(s): Mark A. Ratner, Abraham Nitzan, Misha Galperin
Current experimental efforts are clarifying quite beautifully the nature of charge transport in so-called molecular junctions, in which a single molecule provides the channel for current flow between two electrodes. The theoretical modeling of such structures is challenging, because of the uncertainty of geometry, the nonequilibrium nature of the process, and the variety of available mechanisms. The talk will center on the first formulation of the problem in terms of scattering theory, and then on the generalizations needed to make that simple picture relevant to the real experimental situation. These include vibronic coupling, structural disorder and energy transfer. Some comments will be made on possible switching and rectification schemes.
MOLpull: A tool for molecular free energy reconstruction along a pulling coordinate
24 Aug 2010 | Tools | Contributor(s): Lisa Felberg, Ignacio Franco, Martin McCullagh, Mark Ratner, George C. Schatz, Marcelo Carignano
Estimates the force required for stretching a molecule and determines the potential of mean force along the extension coordinate.
PNP Cyclic Peptide Ion Channel Model
04 Apr 2007 | Tools | Contributor(s): Brian Radak, Hyonseok Hwang, George C. Schatz, Mark A. Ratner
This tool simulates ion flow in a system modeled after cyclic peptide ion channels using Poisson-Nernst-Planck (PNP) theory.
Quantum Chemistry Part I
08 Jul 2004 | Online Presentations | Contributor(s): Mark A. Ratner
This tutorial will provide an overview of electronic structure calculations from a
chemist's perspective. This will include a review of the basic electronic structure
TRANSpull: computes pulling coupled to transport properties of single molecules.
27 Jul 2011 | Tools | Contributor(s): Jason Hutcheson, Ignacio Franco, Renaud Nicolas, Marcelo Carignano, Mark Ratner, George C. Schatz
Calculates the electronic transport properties of single molecules as they are mechanically elongated.