Chemistry Faculty:
Wesley D Allen, Ph.D.
Associate Professor
Phone: 706-542-7729
E-mail: wdallen@uga.edu
Biographical Information
Associate Professor (2008 - present)
Adjunct Professor and Graduate Faculty Member, Department of Chemistry, University of Georgia (2005-2008)
Senior Research Scientist, Center for Computational Chemistry, University of Georgia (1995-2008)
Assistant Professor, Department of Chemistry, Stanford University (1988-1994)
Postdoctoral Research Associate, Combustion Research Facility, Sandia National Laboratories, Livermore, CA (1987-88)
Ph. D. (Theoretical Chemistry) University of California, Berkeley (1987)
B. A. (Chemistry & Physics) Vanderbilt University (1983)
Research Interests
My research at the Center for Computational Chemistry involves theoretical development and computational applications of ab initio molecular quantum mechanics, thus relying on the foundations of electronic structure theory to investigate diverse chemical problems. A wide array of graduate-research opportunities is available for those whose interests range from a focus on chemical problems using computations as a tool of discovery, to the abstract development of theoretical formalisms and mathematical algorithms, to the programming of practical, state-of-the-art computer codes. The following is an illustrative but not exhaustive list of topics we have recently investigated.
Chemical applications
Combustion chemistry: soot formation mechanisms; alkyl + O2 reactions; the HCCO, NCO, and NCCO intermediates; the surprising existence of enols in flames
Pyrolysis of aromatic species: the unimolecular decomposition of ortho-benzyne
Neutral and cationic carbon clusters C3-C12
Definitive characterization of building blocks of biomolecules: anchoring the absolute proton affinity scale; exhaustive surveys of conformers of cysteine, serine, and valine; precise re geometries of proline, glycine, and alanine by a combination of microwave rotational constants and theoretical vibration-rotation interaction constants
Secondary structures of peptides and proteins via NMR chemical shielding anisotropy (CSA) parameters
Matrix isolation and identification of novel species with unusual properties: H-C-OH, H-C-SiHCl2, H-C-SiH3, Cl-C-SiCl3, and HNOO
Model systems for probing metal cation hydration by mass-selected infrared photodissociation (IRPD) spectroscopy: V+(H2O)Arn
Vibrational dependence of optical rotation: massive vibrational and thermal averaging in 3-chloro-1-butene
SN2 reactions: definitive structures and energetics for paradigms, failures of density functional theory, tests and applications of Marcus theory, the origin of the benzylic effect
Theoretical development
Multireference coupled-cluster theory
Next-generation explicitly correlated (F12 and R12) electronic structure theory
Focal-point extrapolation schemes for achieving ab initio limits of thermochemistry and spectroscopy
Two-electron basis set incompleteness diagnostics
The cosmological habitable zone for the fine-structure constant and electron/proton mass ratio
Anharmonic force fields and vibrational analyses of polyatomic molecules
Discovery, elucidation, and solution of vibrational frequency anomalies in electronic structure predictions: popular theoretical methods predict benzene and arenes to be nonplanar
Generation and convergence analysis of high-order many-body perturbation series
Resummation techniques for MPn series
Benchmark full configuration interaction studies
Symmetry breaking phenomena in electronic wavefunctions
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Publications
"Analytic Gradients for the State-Specific Multireference Coupled Cluster Singles and Doubles Model," Eric Prochnow, Francesco A. Evangelista, Henry F. Schaefer III, Wesley D. Allen, and Jurgen Gauss, J. Chem. Phys. 131, 064109: 1-12 (2009).
"Conformers of Gaseous Cysteine," Jeremiah J. Wilke, Maria C. Lind, Henry F. Schaefer III, Attila G. Csaszar, and Wesley D. Allen, J. Chem. Theory Comput. 5, 1511-1523 (2009).
"A Companion Perturbation Theory for State-Specific Multireference Coupled Cluster Methods," Francesco A. Evangelista, Andrew C. Simmonett, Henry F. Schaefer III, Debashis Mukherjee, and Wesley D. Allen, Phys. Chem. Chem. Phys. 11, 4728-4741 (2009).
"Optical Activity in Conformationally Flexible Molecules: A Theoretical Study of Large-Amplitude Vibrational Averaging in (R)-3-Chloro-1-butene," T. Daniel Crawford and Wesley D. Allen, Mol. Phys. 107, 1041-1057 (2009).
"A Hierarchy of Homodesmotic Reactions for Thermochemistry," Steven E. Wheeler, Kendall N. Houk, Paul v. R. Schleyer, and Wesley D. Allen, J. Am. Chem. Soc. 131, 2547-2560 (2009).
"The Enthalpy of Formation and Anharmonic Force Field of Diacetylene," Andrew C. Simmonett, Henry F. Schaefer III, and Wesley D. Allen, J. Chem. Phys. 130, 044301: 1-10 (2009).
"Origin of the SN2 Benzylic Effect," Boris Galabov, Valia Nikolova, Jeremiah J. Wilke, Henry F. Schaefer III, and Wesley D. Allen, J. Am. Chem. Soc. 130, 9887-9896 (2008).
"Anchoring the Absolute Proton Affinity Scale," Gabor Czako, Edit Matyus, Andrew C. Simmonett, Attila G. Csaszar, Henry F. Schaefer III, and Wesley D. Allen, J. Chem. Theory Comput. 4, 1220-1229 (2008).
"Capture of Hydroxymethylene and Its Fast Disappearance through Tunnelling," Peter R. Schreiner, Hans Peter Reisenauer, Frank C. Pickard, Andrew C. Simmonett, Wesley D. Allen, Edit Matyus, and Attila G. Csaszar, Nature 453, 906-909 (2008). See commentaries and news articles on this work in Nature (Vol. 453, p. 862), Chemistry World (July 2008, p. 23), and Angewandte Chemie (Vol. 47, p. 2).
"Triple Excitations in State-Specific Multireference Coupled Cluster Theory. Application of Mk-MRCCSDT and Mk-MRCCSDT-n Methods to Model Systems," Francesco A. Evangelista, Andrew C. Simmonett, Wesley D. Allen, Henry F. Schaefer III, and Jurgen Gauss, J. Chem. Phys. 128, 124104: 1-13 (2008).
"Establishment of the C2H5 + O2 Reaction Mechanism: A Combustion Archetype," Jeremiah J. Wilke, Wesley D. Allen, and Henry F. Schaefer III, J. Chem. Phys. 128, 074308: 1-9 (2008).
"On the Convergence of Z-Averaged Perturbation Theory (ZAPT)," Steven E. Wheeler, Wesley D. Allen, and Henry F. Schaefer III, J. Chem. Phys. 128, 074107: 1-11 (2008).
"Ionization Thresholds of Small Carbon Clusters: Tunable VUV Experiments and Theory," Leonid Belau, Steven E. Wheeler, Brian W. Ticknor, Musahid Ahmed, Stephen R. Leone, Wesley D. Allen, Henry F. Schaefer III, and Michael A. Duncan, J. Am. Chem. Soc. 129, 10229-10243 (2007).
"In Search of Definitive Signatures of the Elusive NCCO Radical," Andrew C. Simmonett, Francesco A. Evangelista, Wesley D. Allen, and Henry F. Schaefer III, J. Chem. Phys. 127, 014306: 1-9 (2007).
"Unimolecular thermal fragmentation of ortho-benzyne," Xu Zhang, Alan T. Maccarone, Mark R. Nimlos, Shuji Kato, Veronica M. Bierbaum, G. Barney Ellison, Branko Ruscic, Andrew C. Simmonett, Wesley D. Allen, and Henry F. Schaefer, J. Chem. Phys. 126, 044312 (2007).
"In Search of Definitive Signatures of the Elusive NCCO Radical," Andrew C. Simmonett, Francesco A. Evangelista, Wesley D. Allen, and Henry F. Schaefer III, J. Chem. Phys. 127, 014306: 1-9 (2007).
"Model Systems for Probing Metal Cation Hydration: The V+(H2O) and ArV+(H2O) Complexes," Veronika Kasalova, Wesley D. Allen, Henry F. Schaefer III, Emmanuel D. Pillai, and Michael A. Duncan, Roger E. Miller Memorial Issue, J. Phys. Chem. A 111, 7599-7610 (2007).
"Coupling Term Derivation and General Implementation of State-Specific Multireference Coupled Cluster Theories," Francesco A. Evangelista, Wesley D. Allen, and Henry F. Schaefer III, J. Chem. Phys. 127, 024102: 1-17 (2007).
"Thermochemistry of Key Soot Formation Intermediates: C3H3 Isomers," Steven E. Wheeler, Kenneth A. Robertson, Wesley D. Allen, Henry F. Schaefer III, Yannick J. Bomble, and John F. Stanton, J. Phys. Chem. A 111, 3819-3830 (2007).
"PSI3: An Open-Source Ab Initio Electronic Structure Package," T. Daniel Crawford, C. David Sherrill, Edward F. Valeev, Justin T. Fermann, Rollin A. King, Matthew L. Leininger, Shawn T. Brown, Curtis L. Janssen, Edward T. Seidl, Joseph P. Kenny, and Wesley D. Allen, J. Comput. Chem. 28, 1610-1616 (2007).