Crystal orbital calculation of coupled Hartree-Fock dynamic (hyper)polarizabilities for prototype pi-conjugated polymers

Ab initio static and dynamic (hyper)polarizability calculations at the time -dependent coupled-perturbed Hartree-Fock level have been carried out on po lyyne, all-trans polyacetylene (PA), and trans-transoid polymethineimine by a noniterative method. The dependence on basis set and on the number of ne ighboring unit cells exactly included has been investigated. The 6-31G basi s set with nine neighboring unit cells, and long-range Coulomb interactions taken into account, was utilized in the final calculations. Although in ma ny instances our results are the first that have been obtained we compare w ith oligomer calculations wherever possible. For PA the theoretical result is also compared with experiment and the main reasons for the existing disc repancy are addressed. (C) 2001 American Institute of Physics.