Professor of Chemistry and Biochemistry
University of Delaware
4 Kent Way
Newark, DE 19716
B.S., 1979, University of California, Berkeley; M.A.,
1981, Ph.D., 1986, Harvard University; Postdoctoral Member of Technical
Staff, 1986 – 1988, AT&T Bell Laboratories
group applies theoretical and computational methods to a wide range of
problems in chemistry and materials science. These problems include
semiconductor surface chemistry, electron conduction through molecules,
solar fuel production, formation of atmospheric aerosols, and solvation
in supercritical water. Our work concentrates on problems of current
interest to experimenters and many of these projects involve direct
collaborations with experimental groups. However, we are primarily
interested in predicting new chemistry that has not yet been studied
experimentally, or extending our understanding to situations where
experiments are not possible. Most of our work involves first-principles
electronic structure methods (also known as quantum chemistry), but we
generally apply these methods in novel ways, often in combination with
As an example of our
approach, we are currently studying how electrical currents are
conducted through organic molecules attached to semiconductor surfaces.
Our goal is to support development of materials for new generations of
electronic devices, as well as to build a fundamental understanding of
electrical conductivity at the atomic scale. The figure illustrates one
application in which rows of styrene molecules are bonded to a silicon
surface (of which only a small part is shown in the upper figure).
electrical conductance of these molecules can be measured with a
scanning tunneling microscope (STM) and we have developed theoretical
tools for predicting how the electrical current measured with STM is
related to the molecular structure.For styrene on silicon, we find that
the current depends strongly on the orientation of the phenyl ring, so
that the molecule at the end of the row has a brighter feature in the
STM image (lower figure) than the others. This enhanced conductance at
the end of styrene rows has been seen experimentally, but its connection
to molecular geometry could only be uncovered with theory. This result
suggests that subtle changes in molecular structure can be used to
control flow of electrical currents.
related work, we are studying how the electronic properties of
photocatalysts such as zinc gallium oxynitride may be modified by
controlling their composition or doping with impurities. The goal is to
develop new materials for generating chemical fuels from solar energy.
also develop new theoretical methods to make useful predictions in
regimes that are not accessible to experiment. For example, in
collaboration with Prof. Wood, we are developing a new method for
modeling solvation energies, combining the ability of molecular dynamics
to model the structural variety in solutions and the ability of
first-principles calculations to determine accurate energies for those
structures. This method has allowed us to predict solvation energies in
supercritical water, where other methods fail. Our method can be applied
to very high temperatures and pressures, which are important for
understanding geochemical and industrial processes, but which cannot be
reproduced in the laboratory. We are using the same idea to model the
kinetics of aerosol formation, an important process in atmospheric
chemistry that contributes to cloud formation and is an essential
component in determining the global climate.
- A. M. Shough, D. J. Doren and R. F. Lobo “A Visible Light Photocatalyst: Effects of Vanadium Substitution on ETS-10,” Phys. Chem. Chem. Phys., (2007) 9, 5096.
- L. Yang and D.J. Doren “Structure of Styrene Molecular Lines on Si(100)-2x1:H,” J. Phys. Chem. C, (2008) 112, 781.
Liu, R.H. Wood and D.J. Doren “Sodium Chloride in Supercritical Water
as a Function of Density: Potentials of Mean Force and an Equation for
the Dissociation Constant from 723 to 1073 K and from 0 to 0.9 g/cm3,” J. Phys. Chem. B, (2008) 112, 7289.
- A.M. Shough, D. J. Doren and D.M. Di Toro “Polyfunctional Methodology for Improved DFT Thermochemical Predictions,” J. Phys. Chem., (2008) 112, 10624.
Shough, D.J. Doren and B. Ogunnaike “Transition Metal Substitution in
ETS-10: DFT Calculations and a Simple Model for Electronic Structure
Prediction,”Chem. Materials, (2009) 21, 1232.
Rahaman, A.C.T. van Duin, V.S. Bryantsev, J.E. Mueller, S.D. Solares,
W.A. Goddard and D.J. Doren “Development of a ReaxFF Reactive Force
Field for Aqueous Chloride and Copper Chloride,” J. Phys. Chem. A, (2010) 114, 3556.
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