J. Phys. II France
Volume 5, Numéro 1, January 1995
Page(s) 63 - 74
DOI: 10.1051/jp2:1995100
J. Phys. II France 5 (1995) 63-74

On Some Attempts to Generalize the Effective Hamiltonian Approach

J. L. Heully1, S. Evangelisti2 and Ph. Durand1

1  Laboratoire de Physique Quantique URA 505 du CNRS, Université Paul Sabatier, 118 route de Narbonne 31062 Toulouse Cedex, France
2  Dipartimento di Chimica Fisica e Inorganica, Universita di Bologna, Viale Risorgimento 4, 40136 Bologna, Italy

(Received 18 July 1994, received in final form 10 October 1994, accepted 17 October 1994)

A clear and simple method to derive various intermediate Hamiltonians is proposed. Several intermediate Hamiltonians usable for various purposes are presented. The new intermediate Hamiltonians have the same properties as the traditional effective Hamiltonians but they should present better convergence properties, and should avoid any intruder state problem.

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