Bulk properties from finitehyphen;cluster calculations. VI. A finitehyphen;size perturbation theory for the Hartreendash;Fock energy of linear oligomers

摘要

A finitehyphen;size perturbation theory that expresses the total Hartreendash;Fock energy and the orbital energies of a finite nonmetallic linear oligomer composed ofNidentical unit cells as power series in ngr;=Nminus;1is derived. The coefficients for the first three terms of these series are evaluated explicitly through the first order of the Hartreendash;Fock formalism. The form of the uncoupled secondhyphen;order contributions is discussed. The resulting expressions contain infinite sums involving the Wannier orbitals of the bulk polymer. The presence of nonanalytic terms in the expansion is also commented upon.