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New Semi-empirical Approach for the Calculation of13C Chemical-Shift Tensors

✍ Scribed by Ulrich Sternberg; Wolfram Prieß

Publisher
Elsevier Science
Year
1997
Tongue
English
Weight
289 KB
Volume
125
Category
Article
ISSN
1090-7807

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✦ Synopsis

The semi-empirical bond polarization theory is applied to the calchemical calculations on the IGLO (3), GIAO (4), or culation of 13 C chemical-shift tensors. This method allows prediction LORG (5) level must be performed if chemical-shift tensors of shift tensors with deviations from experiment comparable to the are to be understood with respect to the structure of a moleerrors of the ab initio methods. In contrast to ab initio calculations, cule. This approach is limited to medium-size molecules that a set of empirical parameters is needed, which can be estimated from do not interact too strongly with their neighbors within the experimental chemical-shift tensors solving a set of linear equations. crystal lattice, as for instance naphthalene. If tensorial data

The coefficients of this overdetermined set of equations are bond is to be used in molecular mechanics calculation, the compupolarization energies that must be calculated within the framework tational effort of the ab initio methods inhibits its application.

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