Calculation of ab initio dynamic hyperpolarizabilities of polymers

The coupled Hartree-Fock (CHF) equations in second order are derived to cal culate dynamic polarizabilities and hyperpolarizabilities for infinite peri odic chains. The analytical expressions for the second derivatives of the p erturbed crystal orbitals with respect to the quasimomentum k are developed . The first and second derivatives are required on behalf of the definition of the perturbation operator describing the effect of the time-dependent e lectric field on the electronic structure of the polymer. The computer prog ram has been applied to calculate the tensor elements of the second-harmoni c generation and the optical rectification for the model chain poly(water) and the conjugated pi-electron system poly(carbonitrile), respectively. The CHF-results are compared with uncoupled Hartree-Fock (UCHF) calculations. (C) 1999 American Institute of Physics. [S0021-9606(99)50403-0].