Valence Bond Charge Transfer Theory for Predicting Nonlinear Optical Properties of Organic Materials
A simple theory (VB-CT) is developed for predicting nonlinear optical properties of organic materials. Application of this theory to donor-acceptor charge-transfer molecules leads to analytic formulae for the absorption frequency, hyperpolarizabilities, and bond length alternation. Derivative relationships between hyperpolarizabilities (with respect to bond length alternation) are derived. Using a continuum description of the solvent in the VB-CT framework leads to the VB-CT-S model which gives results for solvent shifts in good agreement with experiment. To predict the saturation behavior of polarizability and hyperpolarizability with respect to polymer length, we developed the VB-CTE model which is applied to nine polymeric materials.
© 1995 American Chemical Society. Received October 28, 1994. Published in print 31 March 1995. We thank Seth Marder of the Beckman Institute for helpful discussions. This research was funded by NSF (CHE 91-100289 and ASC 92-17368). The facilities of the MSC are also supported by grants from DOE-AICD, Allied-Signal Corp., Asahi Chemical, Asahi Glass, Chevron Petroleum Technology, Hughes Research Laboratories, BF Goodrich, Vestar, Xerox, and Beckman Institute. Some calculations were carried out on the NSF-Pittsburgh supercomputer and on the JPL CRAY.