Daniel M. Chipman Iowa State University, B.S. ('67) University of Wisconsin, Ph.D. ('72) Tel. (574) 631-5562 e-mail: chipman.1@nd.edu Electronic Structure in Solution

Scientific Interests

Theoretical studies of free radicals — vibrational force fields; spin density; excitation energy; large amplitude internal motion

Solvation effects — reaction field modeling; hydrogen bonding; ionic strength effects; dispersion and cavitation corrections

Recent Accomplishments | Top |

Excitation of Water — The lowest excited electronic state of water is well known to be dissociative in an isolated gas phase monomer. However, we have established that the excited potential surface instead becomes quasibound when the OH moiety is hydrogen bonded to a neighboring water molecule. This has important ramifications for the behavior of excited liquid water and ice, newly raising the possibility of energy transport over substantial distances by migration of a neutral exciton.

Solvation Effects — The ultraviolet absorption peak commonly used to identify hydroxyl radical in aqueous solution has been computationally shown to be mainly due to a novel charge-transfer-from-solvent electronic transition that is prominent when OH is hemibonded, rather than more stable hydrogen bonded, to H₂O. The hemibonding interaction can be as much as half as strong as the more stable hydrogen bonding interaction, and is significant over a substantial geometrical region. In other work, it has been shown that anions become smaller and cations larger when placed in a polar solvent. These counterintuitive trends are explained in terms of screening or descreening by the solvent electric field of electron-electron repulsions in the solute periphery.

Selected Publications | Top |

Pomogaeva, A., Thompson, D.W. and Chipman, D.M.
Modeling short-range contributions to hydration energies with minimal parameterization
Chem. Phys. Lett. 2011 511, 161-5 link

D.M. Chipman
Hemibonding between hydroxyl radical and water
J. Phys. Chem. A 2011 115, 1161-1171 link

P. Cabral do Couto and D.M. Chipman
How does dielectric solvation affect the size of an ion?
J. Phys. Chem. A 2010 114, 12788-12793 link

P. Cabral do Couto and D.M. Chipman
Insights into the ultraviolet spectrum of liquid water from model calculations
J. Chem. Phys. 2010 132, 244307/1-11 link

D.M. Chipman
Vertical electronic excitation with a dielectric continuum model of solvation. I. Theory
J. Chem. Phys. 2009 131, 014103/1-10 link

D.M. Chipman
Vertical electronic excitation with a dielectric continuum model of solvation. II. Implementation and applicationss
J. Chem. Phys. 2009 131, 014104/1-6 link

Supported by the Division of
Chemical Sciences
Office of
Basic Energy Sciences
at the
U.S. Department of Energy

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Last Modified: 10/14/2011