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Pure Appl. Chem., Vol. 71, No. 10, pp. 1919-1981, 1999

Glossary of terms used in theoretical organic chemistry

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> Abstract
> General Remarks
> Arrangement

> Fundamental physical constants used in the glossary
> References

> Glossary of terms
> Appendix. Glossary of acronyms of terms used in theoretical organic chemistry

General Remarks

Recent years have seen a deep penetration of the language, concepts and methods of quantum chemistry, statistical mechanics and graph theory into the conceptual system of organic chemistry and cognate fields. The terminology of modern quantum chemistry interlaces with that of classical electronic and resonance theories, and the use of new technical terms, methodologies and acronyms proliferated. This process necessitates examination of the terms used in theoretical organic chemistry for meaning, utility and consistence. Although theoretical organic chemistry cannot be separated from theoretical chemistry itself, it constitutes a significant part of the latter representing the domain of physical organic chemistry associated with theoretical modeling of reaction mechanisms, computational studies of structural, thermodynamic, spectroscopic and other physical properties of organic compounds, and has grown tremendously. A need has, therefore, been recognized for providing an organic chemist, who uses in the research modern methodologies or is interested in their comprehension, with the relevant operational definitions or explanations of frequently employed notions and concepts. For this purpose, concise introductory descriptions and leading references (to original sources, important reviews or monographs) are given for a number of important terms.

The Glossary may be considered as a supplement to the comprehensive compendium (IUPAC: Organic Chemistry Division: Commission on Physical Organic Chemistry. Glossary of Terms Used in Physical Organic Chemistry.) of terminology traditionally established in physical organic chemistry. Therefore, the styles of the presentation of the material in both Glossaries are basically similar. The general criteria adopted for inclusion of a term into the Glossary were: (a) its wide use in the literature; (b) uncertainty or ambiguity in its current use. There is almost no overlap in included terms between the two Glossaries. This Glossary is supplemented by a list of most frequently encountered (about 200) acronyms used in the literature on theoretical organic chemistry (appendix). This list is intentionally much shorter than that of the parallel project "Acronyms used in Theoretical Chemistry" (Pure Appl. Chem., 1996, 68 (No. 2), 387-456) developed by the Physical Chemistry Division which includes a giant number (about 2500) of specific acronyms and abbreviations, e.g. those of numerous program packages, and covers areas of application far beyond those of primary interests of organic and physical organic chemists.

The Commission considers it necessary to emphasize that the primary objective of the Glossary is to serve as an update and consistent reference to terminology used in theoretical organic chemistry and cognate fields. There is no intention to impose any restrictions or rules on the use of the recommended terminology.

The Commission and the Working Party gratefully acknowledge important contributions of many scientists who helped by proposing or defining certain terms as well as providing useful criticisms and advice. The following names are to be mentioned: A. Dneprovskii A. Katritzky M. Yanez, E. Eliel A. Levin, E. Halevi I. Stankevich, R. Hoffmann R. Thummel

The work was coordinated with that of Working Party on Theoretical and Computational Chemistry in the Physical Chemistry Division.


The arrangement is alphabetical. Italicized words in the body of a definition, as well as those given at the end, point to relevant cross-references. No distinction is made between singular and plural in cross-referencing. Capitalized names indicate references which are either those where the term was originally defined or pertinent review articles or monographs where it is used.

Fundamental Physical Constants Used in the Glossary*

Atomic mass constant (unified atomic mass unit) mu = 1u = 1.6605402(10) x 10-27 kg

Bohr radius a0 = 4pe0(h/2p)2/mee2 = 5.29177249(24) x 10-11 m

Electron rest mass me = 9.1093877(54) x 10-31 kg

Elementary charge e = 1.60217733(49) x 10-19 C

Energy in hartrees Eh = (h/2p)2/mea02 = 4.3597482(26) x 10-18 J

Permittivity of vacuum e0 = 8.854187816 x 10-12 F m-1

Speed of light in vacuum c0 = 299792458 m s-1 (defined)

Planck constant h = 6.6260755(40) x 10-34 J s

Boltzmann constant k = 1.380658(12) x 10-23 J K-1

Avogadro constant NA = 6.0221367(36) x 1023 mol-1

* Mills, I., Cvitas, T., Homann, K., Kallay, N., and Kuchitsu, K. "Quantities, Units and Symbols in Physical Chemistry" — The Green Book, 2nd Edition, Blackwell Sci., 1993.

[A] [B] [C] [D] [E] [F] [G] [H] [I] [J-K] [L]
[M] [N] [O] [P] [Q-R] [S] [T] [U-V] [W] [X-Y-Z]

> Abstract
> General remarks
> Arrangement

> Fundamental physical constants used in the glossary
> References
> Appendix. Glossary of acronyms of terms used in theoretical organic chemistry

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