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Department Chair
Professor, Physical Chemistry
B.S. in Chemistry 1973, University of Illinois
at
Urbana-Champaign
B.S. in Physics 1973, University of Illinois at
Urbana-Champaign
Ph.D. 1976, University of California at Berkeley
Email: dykstra@ilstu.edu
Phone: (309)438-7661
Office: 214 Julian Hall
Our investigations involve the development and application of models, theories, and
computational methods for determining molecular structure, energetics, properties, vibrational
effects, and interactions. We try to construct uniform, extendable procedures that have long-term utility.
Ab initio electronic structure theory is a cornerstone of our efforts. We have devised a number of
techniques for electron correlation and for the direct evaluation of numerous molecular properties,
e.g., dipole and higher order electrical moments, polarizabilities, hyperpolarizabilities, chemical
shieldings, and magnetic susceptibilities.
A major area of study in recent years has been intermolecular interaction, and our interests have
focused on ((i) studying small, weakly bound clusters through ab initio (quantum mechanical)
calculations, (ii) developing and applying ab initio methods for molecular response properties needed
for model potentials, (iii) employing model potentials to examine growth of large clusters,
and (iv) investigating certain dynamical (vibrational) features of small to clusters. An
emerging, connected interest is on a class of problems which have the potential for impacting several
technologies including hydrogen fuel storage, geological and materials entrapment of carbon dioxide, and
biomolecular modeling of slippery energy landscapes.
Quadrupolar molecules have become a special interest. These are neutral molecules that have a zero
permanent dipole moment but a non-zero quadrupole moment (e.g., H2, N2, HCCH, ethane, benzene, allene,
and transoid-glyoxal). There are extended species with similar, but local quadrupolar fields. For instance,
polyynes,
H(CC)nH, have interaction sites that correspond to the influence of local –CC– quadrupoles.
The orientational and translational features of the interactions among quadrupolar species, such as
benzene, are simply not like those of dipole-dipole interacting species. There are special structural,
energetic, and dynamical manifestations. For instance, in a regular close-packing arrangement of hundreds
of H2 molecules, each embedded molecule has 12 nearest neighbors oriented in a way that corresponds to different,
favorable quadrupole-quadrupole interactions. The potential for rotating a single molecule with surrounding
molecules fixed has a substantial barrier: The nearest neighbor interactions essentially lock the
orientation. Remarkably, the barrier goes almost to zero because the nearest neighbor molecules can
re-orient in a concerted manner.
Quadrupolar molecules aggregate uniquely. They tend to have numerous binding sites (multiple minima),
surface flatness that allows for especially wide-amplitude vibrational excursions, and often
energetically-competitive packing arrangements. Small perturbations (fields, conformational changes,
other nearby molecules, atoms, and ions) can have sharper effects than for clusters of dipolar molecules.
Some features may not yet have been recognized, and clearly, the translation of molecular properties into
surface features and then into dynamical effects remains an open issue. It is likely to be an important
issue for biomolecular and materials simulations in the years ahead.
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SELECTED PUBLICATIONS
H. M. Jaeger, D. W. H. Swenson and C. E. Dykstra, J. Phys. Chem. A 110, 6399 (2006); Remarkable Features in the Interactions of Quadrupolar Molecules.
K. Chenoweth and C. E. Dykstra, Chem. Phys. Lett. 402, 329-334 (2005); Selecting Weak Bonding Sites: Effect of a Methyl Group in the Acetylene-Polyyne Interaction.
K. Chenoweth and C. E. Dykstra, Chem. Phys. Lett. 400, 153-157 (2004); Pinwheel Binding of Hydrogen Molecules to Acetylene
M. Carmichael, K. Chenoweth, and C. E. Dykstra, J. Phys. Chem. A. 108, 3143-3152 (2004); Hydrogen Molecule Clusters.
Complete List
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