抄録
In order to design organic nonlinear optical materials, several of theoretical calculations are necessary. Within the oriented gas model approximation, nonlinear susceptibilities of organic crystals can be calculated from hyperpolarizabilities of the molecule and the crystal structure. Molecular hyperpolarizabilities can be calculated very precisely by a molecular orbital method.
Theoretical calculations of hyperpolarizabilities of polymers, which are important as third-order nonlinear materials, were done considering their exciton states although there remained several problems to be solved.
The intermolecular interaction effects on hyperpolarizabilities were analysed by super molecule CPHF calculations of ab initio MO method.
