Interface states of alternating trans polyacetylene-polyvinylidenfluoride and polyethylene-polyvinylidenfluoride composite chains

To test a recent fully (mutually) consistent method to treat the interfaces between two solids, these states occuring in two pairs of quasi-one-dimensional systems, were calculated. The investigations dealt with alternating trans-polyacetylene-(PA)-polyvinylidenfluoride (PVDF) and polyethylene-(PE)-polyvinylidenfluoride chains. For these an ab initio self-consistent field linear combination of atomic orbitals technique for determining the band structures of the chains, and a Green's matrix formalism for solving the interface problem was used. The properties of the resulting interface states are discussed. In particular, the importance of the occurrence of extra states in the gap of PA and PE which in the case of better set and especially in 2- and 3-dimensions can lead to "bending bands" at the interface, is emphasized. The extension of the interface calculations to 2- and 3D solids is planned.