ISSN:
1432-2234
Keywords:
Spin density
;
Hyperfine coupling constants
;
Influence of excitation classes
;
Indirect and direct contributions toA iso
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Summary Reliable prediction of the isotropic hyperfine coupling constantA iso is still a difficult task forab initio calculations. Strong dependence on the method employed for its calculation has been found. Within a CI ansatzA 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 onA 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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01122433
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