### Abstract

In models based on valence bond theory for predicting, nonlinear optical properties of push-pull molecules, the wave functions representing resonance structures are assumed to be orthogonal. We have extended the two-state valence bond charge-transfer model to include non-zero overlap integrals. The resulting model leads to analytic formulae for the polarizability and hyperpolarizabilities, which are related to the overlap and other molecular parameters. In particular we report, as a function of the overlap: (i) relatively weak dependence of the first-order polarizability; (ii) significant variations in both the magnitude and the shape of the response curves corresponding to the second- and third-order polarizabilities. This result may be of relevance in the context of optical switching effects induced by chemical changes (related to the overlap) rather than the more conventional field-induced effect.

Original language | English |
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Pages (from-to) | 1805-1811 |

Number of pages | 7 |

Journal | Molecular Physics |

Volume | 101 |

Issue number | 12 |

Publication status | Published - Jun 20 2003 |

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### ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics

### Cite this

*Molecular Physics*,

*101*(12), 1805-1811.