A Monte Carlo study of structure and intercalation in conducting polymers

Monte Carlo (MC) calculations have been used to model the equatorial chain packing within linear ir-conjugated polymers both before and after intercal ation. These calculations employ a generalized anisotropic planar rotor (GA PR) representation of the host lattice through a model Hamiltonian, introdu ced previously in a mean-field theory (MFT) approach by H.-Y. Choi, A.B. Ha rris and E.J. Mele [Phys. Rev. B 40, 3766 (1989)], in which planar rotors ( representing polymer chains) are pinned onto a rigid two-dimensional triang ular lattice. Equilibrium structures and transition temperatures are in goo d agreement with those seen in MFT but additional MC calculations show the possible existence of commensurate phases with larger unit cells than those considered in MFT studies.