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Effective valence bond hamiltonian for the cations of conjugated hydrocarbons
Author(s) -
Gadea Xavier,
Maynau Daniel,
Malrieu JeanPaul
Publication year - 1984
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.560260102
Subject(s) - hamiltonian (control theory) , delocalized electron , transferability , valence bond theory , conjugated system , chemistry , valence (chemistry) , molecule , formalism (music) , quantum mechanics , physics , computational chemistry , atomic physics , molecular orbital , mathematics , mathematical optimization , statistics , organic chemistry , art , musical , visual arts , logit , polymer
Previous papers have developed magnetic effective valence bond (EVB) Hamiltonians for the neutral states of π systems; following the same philosophy and using either the quasidegenerate perturbation theory or wave operator formalism, other EVB + Hamiltonians may be derived for the lowest states of positively charged conjugated hydrocarbons. Their effective operators introduce both charge delocalization (which plays a much more direct role than for the neutral molecules) and effective spin ordering effects. The transferability and efficiency of this EVB + Hamiltonian are tested by comparison with the exact solutions of the full PPP Hamiltonians. The resulting spectrum is much more dense than in the Koopmans' description; non‐Koopmans' states are identified for a few molecules. The applicability of the model to the d bands of metals is discussed in terms of the β/ U ratio.