Study of influences of various excitation classes on ab initio calculated isotropic hyperfine coupling constants
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- Reliable prediction of the isotropic hyperfine coupling constant A\(_{iso}\) is still a difficult task for ab initio calculations. Strang dependence on the method employed for its ca1culation has been found. Within a CI ansatz A\(_{iso}\) is considerably affected by the excitation classes taken into account within the CI calculation. In the present work the influence of various excitation classes on A\(_{iso}\) is examined. Calculations including all single, double, triple and a large part of the quadruple excitations are performed and theReliable prediction of the isotropic hyperfine coupling constant A\(_{iso}\) is still a difficult task for ab initio calculations. Strang dependence on the method employed for its ca1culation has been found. Within a CI ansatz A\(_{iso}\) is considerably affected by the excitation classes taken into account within the CI calculation. In the present work the influence of various excitation classes on A\(_{iso}\) is examined. Calculations including all single, double, triple and a large part of the quadruple excitations are performed and the individual effects of the excitation classes are studied. It is found that the surprisingly good agreement found for S-CI treatments is due to large error cancellations. The importance of higher than double excitations arises from their indirect influence on the single excitations.…
Autor(en): | Bernd Engels |
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URN: | urn:nbn:de:bvb:20-opus-58973 |
Dokumentart: | Artikel / Aufsatz in einer Zeitschrift |
Institute der Universität: | Fakultät für Chemie und Pharmazie / Institut für Organische Chemie |
Sprache der Veröffentlichung: | Englisch |
Erscheinungsjahr: | 1993 |
Originalveröffentlichung / Quelle: | In: Theoretica Chimica Acta (1993) 86, 429-437. |
Allgemeine fachliche Zuordnung (DDC-Klassifikation): | 5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften |
Normierte Schlagworte (GND): | Organische Chemie |
Freie Schlagwort(e): | Hyperfine coupling constants; Indirect and direct contributions to A<sub>iso</sub>; Influence of excitation classes; Spin density |
Datum der Freischaltung: | 24.10.2011 |
Lizenz (Deutsch): | Deutsches Urheberrecht |