Static (hyper-)polarizabilities of infinite, conjugated polymers in the framework of density-functional theory

It is shown how the effects of an external electrostatic held on infinite, conjugated polymers can be included directly in a density-functional method for electronic-structure calculations. In the simpler case that the field does not break the translational symmetry, our tests results for the H-2 mo lecule show that our computational method is reliable, and our results for trans-polyacetylene and polycarbonitrile demonstrate the effects of the pre sence of heteroatoms in the backbone as well as that the electronic propert ies change only a little upon also strong external fields. Finally, we pres ent a method with which these fields can also be treated in the case that t hey break the translational symmetry of the polymer.