Finite-field calculations of the second-order hyperpolarizabilities γ of molecules in solutions

The results of the semi-empirical computation of the second-order hyperpolarizabilities gamma for molecules in the gas phase and in solutions are presented. The finite-field formalism was used to calculate individual components of gamma tensors. The solvent effect was included via the quantum-mechanical Langevin dipoles/Monte Carlo approach. The calculations demonstrate the existence of the large solvent effect on the second-order hyperpolarizabilities of the charge-transfer type of non-linear optical chromophores. The calculated gamma values, including the solvent effect, are compared with experimental data determined in solution phase THG measurements. (C) 1998 Published by Elsevier Science B.V. All rights reserved.