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Exact nonlinear optical coefficients of quantum cell models with interacting electrons
Author(s) -
Soos Z. G.,
McWilliams P. C. M.,
Hayden G. W.
Publication year - 1992
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.560430107
Subject(s) - polydiacetylenes , conjugated system , electron , molecule , molecular physics , nonlinear system , quantum , chemistry , polymer , spectral line , valence (chemistry) , quantum mechanics , physics , computational chemistry , organic chemistry
Diagrammatic valence‐bond (DVB) methods yield exact dynamic nonlinear optical (NLO) coefficients for π‐electron models of conjugated molecules and polymers. We contrast exact coefficients with mean‐field or Hückel results and discuss several qualitative differences. The length and alternation dependencies of NLO spectra for Pariser–Parr–Pople (PPP) models provide a unified treatment of even‐parity states and two‐photon processes in polyenes, polydiacetylenes, and polysilanes. We emphasize relationships between one‐ and two‐photon spectra, correlation effects involving both parallel and transverse NLO coefficients, and the nature of correlated states in polar conjugated molecules and in polymers with centrosymmetric backbones.