Haque, Azizul ; Mukherjee, Debashis (1984) A Hermitian open-shell many-body perturbation theory for treating intruder states Pramana - Journal of Physics, 23 (5). pp. 651-664. ISSN 0304-4289
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Official URL: http://www.ias.ac.in/j_archive/pramana/23/5/651-66...
Related URL: http://dx.doi.org/10.1007/BF02846688
Abstract
In this paper we have formulated an open-shell many-body perturbation theory (mbpt) that applies to an incomplete model space. The effective Hamiltonian Heff generated in our theory is hermitian. We follow the resolvent-operator based time-dependent formulation ofmbpt of Banerjeeet al, and show quite generally that, by classifying the various determinants spanning the Hilbert space as model valence space P, virtual valence space R and virtual space Q, a diagrammatic MBPT satisfying size consistency can be developed. The chief new features of the theory are (i) manifest hermiticity of Heff; (ii) presence of disconnected diagrams no part of which is a legitimate diagram (irreducible disconnected diagrams); (iii) presence of folded diagrams with components that may be irreducible disconnected diagrams; (iv) a consistent treatment of the variousn-valence sectors of the Hilbert space that may be interacting through H eft if valence-holes are present-in particular a modified treatment of the core-valence separation. The generalisation afforded by the theory offers useful conceptual as well as computational advantages because the convergence difficulty encountered in a complete valence space formulation may be bypassed here by keeping the offending valence space determinants out of the model space. A brief critique of the developmentvis-a-vis the only other general model space development leading to a nonhermitian Heff is also given.
Item Type: | Article |
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Source: | Copyright of this article belongs to Indian Academy of Sciences. |
Keywords: | Many-body Theory; Open Shell Perturbation Theory; Intruder States |
ID Code: | 21894 |
Deposited On: | 23 Nov 2010 09:04 |
Last Modified: | 17 May 2016 06:03 |
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