Charge fluctuations and correlation strength in chemical bonds: First-row homonuclear diatomic molecules
✍ Scribed by M. Yu; M. Dolg; P. Fulde; H. Stoll
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 409 KB
- Volume
- 67
- Category
- Article
- ISSN
- 0020-7608
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✦ Synopsis
We investigate, by means of ab initio calculations, the strength of electron correlations within covalent bonds: the first-row homonuclear diatomics serve as test cases. As an appropriate measure of the correlation strength, we introduce the reduction of the mean-square deviations of the electronic charges in localized orbitals forming a bond. A recently developed population analysis in terms of local operators derived from localized molecular orbitals is thereby used. The correlation-strength parameter depends only weakly on dynamical correlations as test calculations demonstrate. Therefore, the full-valence complete active space self-consistent field Ž . CASSCF approximation is applied in order to study the changes in the correlation strength with changing bond length for different types of bonds. A number of simple rules emerge from this discussion. In addition, we show that charge fluctuations are not only a reliable measure of intrabond correlation effects, but also can be used to monitor intraatomic quasi-degeneracy effects as well as the interdependence within multiple bonds.