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COMMENTS Comment on “Periodicity and Peculiarity in 120 First- and Second-Row Diatomic Molecules” Ray Hefferlin Physics Department, Southern College, Collegedale, Tennessee 37315-0370 Received: January 18, 1995; In Final Form: February 20, 1995
It was a great pleasure to see the feature article “Periodicity and Peculiarity in 120 First- and Second-Row Diatomic Molecules”.l The purpose of this Comment is to put the article in context so that there may be more awareness of the large, and growing, world-wide field of periodicity and periodic systems. This field has been reviewed in a recent report2 which also explains the distinction between physical periodic systems of molecules (e.g., Figure 3 in ref 1) and chemical periodic systems (common in the fields of organic and especially pharmaceutical cnemistry). The study of diatomic molecules, and the construction of physical periodic systems for them, is often a first step for investigators realizing the serious lack of data for small molecules. The research of our world-wide collaborating group (c$ references and citations therein) also began this way3 and soon yielded some initial data forecasts (not ab initio computations, such as Boldyrev, Gonzales, and Simons gave) for d i a t ~ m i c s . Then ~ the periodicity of diatomic ions was de~ c r i b e d . ~A theoretical foundation for molecular periodic systems was first formulated in terms of Kroenecker matrix products (where the originating matrix is the chart of the This formulation led immediately to the generalization of the periodic system concept to triatomic and larger molecules.6s8 Demonstrations that the periodic systems for triatomicg and tetraatomic molecules are faithful to many different data are being readied for publication. Finally, a more fundamental theoretical formulation, based on group dynamics, has been presented,10-’2 and comparisons with data for diatomics are essentially complete. The paper by Boldyrev, Gonzales, and Simons analyzes the ground-state symmetries of all first- and second-row diatomic molecules in terms of the number of valence electrons and the
aupau principle, the chemists’ most commonly used periodicity device, and hence makes a significant contribution to the field discussed in this Comment. In addition, they provide new computed data for 25 diatomics whose ground states had been previously not known. I sincerely hope that they will carry on the work for more diatomic species.
References and Notes (1) Boldyrev, A. I.; Gonzales, N.; Simons, J. Periodicity and Peculiarity in 120 First- and Second-Row Diatomic Molecules. J. Phys. Chem. 1994, 98, 9931-9944. (2) Hefferlin, R.; Babaev, E. V.; Burdick, G. W. Periodic Systems of Molecules: Physical and Chemical, Report PHYS-SC 1, 1994, 38 pp. (3) Hefferlin, R.; Campbell, R.; Gimbel, D.; Kuhlman, H.; Cayton, T. The Periodic Table of Diatomic Molecules. I. An Algorithm for Retrieval and Prediction of Spectrophysical Properties. J. Quant. Spectrosc. Radiat. Transfer 1979, 21, 315-336. (4) Hefferlin, R.; Kuhlman, H.; Campbell, R.; Gimbel, D. The Periodic Table of Free Diatomic Molecules. 11. Predicted Internuclear Separations from Curve-Fitted Data. J. Quant. Spectrosc. Radiar. Transfer 1979, 21, 337-354. ( 5 ) Hefferlin, R.; Innis, W. The Differential Coefficient (aP/&)l, for Properties of Diatomic Molecules and Atoms. J. Quanr. Spectrosc. Radiat. Transfer 1983, 24, 97- 112. (6) Hefferlin, R.; Kuhlman, H. The Periodic System for Free Diatomic Molecules. 111. Theoretical Articulation. J. Quant. Spectrosc. Radiat. Transfer 1980, 24, 379-383. (7) Hefferlin, R. Matrix-Product Periodic Systems of Molecules. J. Chem. In5 Comput. Sci. 1994, 34, 314-317. (8) Hefferlin, R. In Periodic Systems and Their Relation to the Systematic Analysis of Molecular Data; Hefferlin, R., Ed.; Edwin Mellen Press: Lewiston, NY, 1989; Chapter 10. (9) Hefferlin, R. A,; Harper, A. M.; Hartman, B. D. The Global Maximum-Stability Periodicities of Various Triatomic-Molecular Properties, Paper FX 44, Division of Atomic, Molecular, and Optical Physics of the American Physical Society, Monterey, CA, May 21-23, 1990. Marsa, R. L.; Cavanaugh, R. J.; Linderman, K. A. Periodic Behavior of Data for MainGroup Triatomic Molecules, Paper TH13, 45th Ohio State Symposium on Molecular Spectroscopy, June 11- 15, 1990. (10) Zhuvikin, G. V.; Hefferlin, R. Periodicheskaya Sistema Dvukhatomnikh Molekul: Teoretiko-gruppovoi Podkhod. Vestn. Leningr. Gosudarstvennovo Univ. 1983, 16, 10-16. (1 1) Zhuvikin, G. F.; Hefferlin, R. Bosonic Symmetry and Periodic Systems of Molecules. In de Olmo, M. A., Santander, M., Guilarte, J. M., Eds. Anales de Fisica. Monografias. Group Theoretical Methods in Physics, Proceedings of the XIX International Colloquium, Salamanca, Spain, June 29-July 4, 1992; Real SOC. Espanola Fis, 1992, 358-361. (12) Zhuvikin, G. V.; Hefferlin, R. Symmetry Principles for Periodic Systems of Molecules, Report JR-PHYS-SCISPBU 1, 1994, 84 pp. JP950180C
0022-3654/95/2099-5222$09.00/0 0 1995 American Chemical Society
