Peter Cummings Research Group Vanderbilt Univeristy
Nanobridge

Molecular Electronics

Single- or multiple-molecule electronic circuits (also known as molecular electronic devices, or MEDs)) have emerged as revolutionary approaches to creating circuits and switches. In MEDs, circuits and switches are each composed of a single molecule with conductance properties that are a function of the molecule’s conformation and hence tunable by external stimulus. To be practical, MEDs need to self-assemble. Thus, a MED could be produced by self-assembly of a multicomponent (conducting molecule plus other species) monolayer on a metal surface. The goal of developing practical molecular electronic circuits is driven by the reality that the continuing fabrication of solid-state electronic devices that obey Moore’s law is reaching fundamental and physical limitations, and becoming extremely expensive. Alternatives such as molecular-based electronic systems may provide a way to construct future computers with ultra dense, ultra fast molecular-sized components. Molecular-scale devices offer several advantages over conventional technology including miniaturization that will allow the scaling of component size to the ultimate level of atoms and molecules. Potential results include dramatically increased computational speed and lower fabrication costs.

A collaboration between researchers at ORNL and our group aims to simulate the chemical assembly, structural properties, and conductance characteristics of self-assembled monolayers (SAMs) relevant to molecular electronics.

Additional information will be added as this project, which began in FY2001, proceeds.

Hartree-Fock and geometry optimization calculations for benzene-dithiol molecules attached to gold atoms. These calculations were perfomed by Predrag Krstic at ORNL with the NWChem chemistry code on the IBM-SP Eagle. Two 100-lattices are shown on the top and bottom. Three benzene-dithiols are seen in the middle area:

Visualizations*

Chime visualizations of molecular dynamics simulations of SAMs of benzenethiol adsorbed onto the 111 surface of Au are available at David Keffer's website. Additional quicktime and/or MPEG movies will be created in the future.

*All Quicktime and MPEG visualizations were created using MDVIZ, developed in our group. See Elwasif, W. R., Moore, J. D., Cummings, P. T., and Ward, R. C., "MDVIZ: A molecular dynamics visualization toolkit," University of Tennessee Department of Computer Science Technical Report UT-CS-99-437. December 1999. UT-CS technical reports can be accessed at http://www.cs.utk.edu/~library/TechReports.html.

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