Isaiah Shavitt
Adjunct Professor of Chemistry
Prof. Shavitt received B.Sc. (1950) and Dipl. Eng. (1951) degrees in chemical engineering from Technion B Israel Institute of Technology, Haifa, Israel; and Ph.D. in theoretical chemistry (1957) from Cambridge University, England. He taught in the chemistry department of Technion (1957-58 and 1962-67), and was a postdoc in theoretical chemistry at the University of Wisconsin (1958-59) and the IBM Watson Laboratory at Columbia University (1960-62). He joined the Columbus Laboratories of Battelle Memorial Institute as Research Leader in 1967, serving concurrently as adjunct professor of chemistry at Ohio State University. He transferred to the chemistry department of Ohio State University full-time in 1981, and retired as emeritus professor in 1994. He has been serving as adjunct professor at the chemistry department of the University of Illinois at Urbana-Champaign since 1996.
Research
The major research interests have been in the field of ab initio methods of electronic structure theory, particularly in configuration interaction (CI), but also including perturbation theory and coupled-cluster theory. The configuration interaction studies emphasized multireference methods, and included the introduction of configuration selection schemes for CI expansions, the Ak and Bk approximate CI methods, and the examination of the convergence behavior of CI expansions and its dependence on the choice of orbitals and expansion terms. The most important methodological contribution has been the development of the graphical form of the unitary group approach (GUGA) and its adaptation for efficient direct multireference configuration interaction and related calculations. The resulting system of computer programs, widely distributed under the name COLUMBUS, is capable of calculations involving billions of terms in the CI expansion (using parallel computing systems). Other methodological contributions included the development of methods for the calculations of multicenter integrals for Slater type orbitals and for the solution of very large matrix eigenvalue problems.
Applications included the calculation of potential energy surfaces, such as H3, H2O, and CH2, and the study of excited states of various molecules, including benzene and butadiene. Other studies compared different methods for the incorporation of electron correlation effects in electronic structure calculations, including perturbation theoretical and coupled cluster methods.
Publications
- R. Shepard, G. S. Kedziora, H. Lischka, I. Shavitt, T. Müller, P. G. Szalay, M. Kállay, and M. Seth, The accuracy of molecular bond lengths computed by multireference electronic structure methods, Chem. Phys., xxx, xxx-xx (2008).
- J. R. Quinn, S. C. Zimmerman, J. E. Del Bene, and I. Shavitt, Does the AΧT or GΧC base-pair possess enhanced stability? Quantifying the effects of CH≅≅≅O interaction and secondary interactions on base-pair stability using a phenomenological analysis and ab initio calculations, J. Am. Chem. Soc., 129, 934-941 (2007).
- I. Shavitt, Are exponential-type basis sets preferable to Gaussians?, Int. J. Quantum Chem., 100, 105-108 (2004).
- J.-L. Kuo, C. V. Ciobanu, L. Ojamäe, I. Shavitt, and S. J. Singer, Short H-bonds and spontaneous self-dissociation in (H2O)20: Effects of H-bond topology. J. Chem. Phys., 118, 3583-3588 (2003).
- J. Karwowski and I. Shavitt, Configuration Intreraction, Chapter 21 in Handbook of Molecular Physics and Quantum Chemistry, Volume 2: Molecular and Electronic Structure (S. Wilson, editor), Wiley, London (2002).
- I. Shavitt, Multi-state multireference Rayleigh Schrödinger perturbation theory for mixed electronic states: Second and third order, Int. J. Mol. Sci. 3, 639-655 (2002).
Awards
- Fellow of the American Physical Society.
- Elected member of the International Academy of Quantum Molecular Science.
- Fellow of the Japan Society for the Promotion of Science, Oct.-Nov. 1980.
- Honoree of International Conference on Molecular Quantum Mechanics: Methods and Applications, Cambridge, England, September 1995.
- Morley Medal of the Cleveland Section of the American Chemical Society, 2000.
