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Effective valence‐shell hamiltonians generated by canonical transformations
Author(s) -
Bradford E. G.,
Westhaus Paul
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560100723
Subject(s) - valence (chemistry) , hamiltonian (control theory) , formalism (music) , shell model , physics , excitation , open shell , coupled cluster , canonical transformation , chemistry , atomic physics , quantum mechanics , molecule , mathematics , quantum , art , mathematical optimization , musical , visual arts
The salient points of applying the canonical transformation‐cluster expansion formalism to the problem of generating effective valence‐shell Hamiltonians are reviewed. Substantial reduction in the strength of the two‐body interaction is found to be in agreement with the semiempirical expectations. The low‐lying excitation spectrum of the carbon atom is calculated by diagonalizing the effective valence‐shell Hamiltonian, and the results agree well with experiment. Use of the formalism for obtaining from first principles the effective one‐and two‐body interactions to be used in very large molecular structure calculations is proposed.