Peter Cummings Research Group Vanderbilt Univeristy

Water and Aqueous Solutions over Wide Ranges of Temperature and Pressure

Water, crucial for the existence of life and an essential component in many industrial and biochemical processes, is without a doubt the most important and most studied substance in nature. Its striking number of unusual properties, such as volume contraction upon melting, extrema in density (maximum) and isothermal compressibility (minimum) at normal conditions, at least nine crystalline polyforms, as well as anomalously large dielectric constant and critical temperature, have been ascribed to its ability to hydrogen-bond and form three-dimensional networks with a rather small number of nearest neighbors, about 4, in comparison to 10-12 for more "normal" liquids.

Most biochemical and industrial processes occur in solution, making it crucial to be able to understand the participation of the solvent, i.e., solvation effects, in determining chemical reactivity. Numerous recent developments have placed an increased interest in supercritical water (SCW) and aqueous solutions. In particular, supercritical water has become an attractive environmentally-friendly reaction medium (solvent) for a variety of chemical processes and technological applications including selective synthesis, coal conversion, deuteration of simple organic compounds, and conversion of organic waste to light feedstocks, where water participates as a solvent, a catalyst, and a reactant. Perhaps the most promising application in this area is the destructive oxidation of biochemical and pharmacological hazardous wastes, known as the supercritical water oxidation (SCWO) process.

Our research program is very diverse and covers many aspects of water and aqueous solutions. These include:



For the past nine years, this research has been conducted in close collaboration with, and in joint leadership with, Ariel Chialvo, ORNL/UT Collaborating Scientist. This research has been primarily supported by the Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences Program, since 1988 through the following grants: DE-FG05-88ER13943 (University of Virginia, 1988-1993) and DE-FG05-94ER14421 (University of Tennessee-Knoxville, 1994 and ongoing). During the period 1988-2001, this project has resulted in over 85 refereed publications and over 100 conference presentations, of which 35 were invited presentations or plenary lectures.

*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

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