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Ron L. Shepard

Senior Chemist (Theoretical Chemistry)


  • Bauxite High School, Bauxite, Arkansas (1970).
  • University of Central Arkansas, Conway, Arkansas. B.S. with majors in Mathematics and Chemistry (1975); Academic and Research Advisor: Prof. J. M. Manion. 
  • University of Utah, Salt Lake City, Utah. Ph.D. in Physical Chemistry (1980); Research Advisor: Prof. J. Simons.
  • Battelle Columbus Laboratories, Columbus, Ohio. Battelle Technical Development Postdoctoral Fellow (1980); Research Advisor: Prof. I. Shavitt. Research Scientist (1981); Supervisor: R. J. Bartlett.
  • Argonne National Laboratory, Argonne, Illinois. Assistant Scientist (1981-1986); Supervisor T. H. Dunning, Jr. Scientist (1986-2007); Supervisors: T. H. Duning, Jr., A. F. Wagner, S. T. Pratt. Senior Scientist (2007-Present); Supervisor S. T. Pratt.

Research Interests

My main interests are the development and application of theoretical and computational methods for gas phase chemistry. I am one of the principal authors of the COLUMBUS Program System <https://​www​.uni​vie​.ac​.at/​c​o​l​u​mbus/> which focuses on multireference methods for molecular electronic structure. At Argonne, these methods are used to compute potential energy surfaces and molecular properties for the ground and excited states of molecules, radicals, and ions involved in hydrocarbon combustion and atmospheric chemistry.

Selected Publications

New Implementation of the Graphical Unitary Group Approach for Multireference Direct Configuration Interaction Calculations,” H. Lischka, R. Shepard, F. B. Brown, and I. Shavitt, Int. J. Quantum Chem. S15, 91 (1981). 

C2Insertion Pathway for BeH2: A Test Problem for the Coupled-Cluster Single and Double Excitation Model,” G. D. Purvis III, R. Shepard, F. B. Brown, and R. J. Bartlett, Int. J. Quantum Chem. 23, 835 (1983). 

The Search for Stationary Points on Surfaces,” A. Banerjee, N. Adams, J. Simons, and R. Shepard, J. Phys. Chem. 89, 52 (1985). 

The Multiconfiguration Self-Consistent Field Method,” R. Shepard, in Ab InitioMethods in Quantum Chemistry II, Advances in Chemical Physics, 69edited by K. P. Lawley (Wiley, New York, 1987) pp. 63-200

Proceedings of the Argonne Integral Evaluation WorkshopInt. J. Quantum Chem. 40(1991) edited by J. Almlöf, R. Shepard, and R. J. Harrison. 

A General MRCI Gradient Program,” R. Shepard, H. Lischka, P. G. Szalay, T. Kovar, and M. Ernzerhof, J. Chem. Phys96, 2085-2098 (1992). 

Ab Initio Molecular Electronic Structure on Parallel Computers,” R. J. Harrison and R. Shepard, Ann. Rev. Phys. Chem45, 623-658 (1994). 

The Analytic Gradient Method for Configuration Interaction Wave Functions,” R. Shepard, in Modern Electronic Structure Theory Part I, edited by D. R. Yarkony, (World Scientific, Singapore, 1995) pp. 345-458

The Subspace Projected Approximate Matrix (SPAM) Modification of the Davidson Method,” R. Shepard, A. F. Wagner, J. L. Tilson, and M. Minkoff, J. Comp. Phys. 172, 472-514 (2001). 

Analytic Evaluation of Nonadiabatic Coupling Terms at the MR-CI Level. I: Formalism,” H. Lischka, M. Dallos, P. G. Szalay, D. R. Yarkony, and R. Shepard, J. Chem. Phys120, 7322-7329 (2004). 

Computing Eigenvalue Bounds for Iterative Subspace Methods,” Y. Zhou, R. Shepard, and M. Minkoff, Computer Physics Comm. 167, 90-102 (2005). 

A General Nonlinear Expansion Form for Electronic Wave Functions,” R. Shepard, J. Phys. Chem. A 109, 11629-11641 (2005). 

The Accuracy of Molecular Bond Lengths Computed by Multireference Electronic Structure Methods”, R. Shepard, G. S. Kedziora, H. Lischka, I. Shavitt, T. Müller, P. G. Szalay, M. Kállay, M. Seth, Chem. Phys. 349, 37-57 (2008). 

COLUMBUS–A Program System for Advanced Multireference Theory Calculations,” H. Lischka, T. Müller, P. G. Szalay, I. Shavitt, R. M. Pitzer, R. Shepard, WIREs Comput. Mol. Sci. 1, 191 (2011). 

Computational and Methodological Elements for Nonadiabatic Trajectory Dynamics Simulations of Molecules,” M. Barbatti, R. Shepard, and H. Lischka, in Conical Intersections: Theory, Computation and Experiment”, W. Domcke, D.R. Yarkony and H. Köppel, Eds., Advanced Series in Physical Chemistry17 (World Scientific, Singapore, 2011) pp. 415-462

Multiconfiguration Self-Consistent Field and Multireference Configuration Interaction Methods and Applications,” P. G. Szalay, T. Mueller, G. Gidofalvi, H. Lischka, R. Shepard, Chem. Rev. 112, 108-181 (2012). 

The Multiradical Character of One- and Two-Dimensional Graphene Nanoribbons,” F. Plasser, H. Pašalić, M. H. Gerzabek, F. Libisch, R. Reiter, J. Burgdörfer, T. Müller, R. Shepard, and H. Lischka, Angewandte Chemie International Edition 52, 2581-2584 (2013).

The Multifacet Graphically Contracted Function Method. I. Formulation and Implementation,” R. Shepard , G. Gidofalvi, and S. R. Brozell. J. Chem. Phys. 141, 064105 (2014). DOI 10.1063/1.4890734

The Representation and Parametrization of Orthogonal Matrices,” R. Shepard, S. R. Brozell, and G. Gidofalvi. J. Phys. Chem. A 119, 7924-7939 (2015). DOI:10.1021/acs.jpca.5b02015

Shavitt Memorial Festschrift Collection,” Theor. Chem. Acc. (2016). ISSN 2194-8666, ISSN 2194-8674 (electronic). Edited by R. Shepard, T. H. Dunning, Jr., and R. M. Pitzer. 

The All Configuration Mean Energy Multiconfiguration Self-Consistent-Field Method I. Equal Configuration Weights,” R. Shepard and S. R. Brozell, Mol. Phys. 117, 2374-2390 (2019). DOI: 10.1080/00268976.2019.1635275.