Orthogonal combined configuration interaction Hylleraas study of two electron atoms
There are two standard variational methods for accounting for electron correlation effects in atoms, namely, the configuration interaction (CI) method and the Hylleraas (Hy) method. This study reports a new method, which combines features of both the CI and Hy methods and is called the orthogonal combined configuration interaction-Hylleraas (CI-Hy) method. In this method the dominant features of the wave function as well as the overall methodology are based on the CI method. In addition, selected terms in the wave function are also of the Hy type, that is, contain interelectronic distances explicitly. As a partial test of the new methodology, calculations were carried out on four states of the helium atom. The energies obtained for the 1/sup 1/S, 2/sup 3/S, s/sup 1/P, and 2/sup 3/P states were -2.903 724 371, -2.175 229 293, -2.123 842 60, and -2.133 163 404 au, respectively, with an error of 6 x 10/sup -9/, 9 x 10/sup -8/, 5 x 10/sup -7/, and 8 x 10/sup -7/ au, respectively, compared to the extremely accurate result of the Pekeris et al. perimetric coordinates calculations. The 1/sup 1/S result is the best non-perimetric coordinates calculation to date. A general, strategy for doing orthogonal CI-Hy calculations for the general n-electron case is postulated and explored in the 2-electron context.
- Research Organization:
- Indiana Univ., Bloomington (USA)
- OSTI ID:
- 5411556
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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