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 π-conjugated polymers both before and after intercalation. These calculations employ a generalized anisotropic planar rotor (GAPR) representation of the host lattice through a model Hamiltonian, introduced previously in a mean-field theory (MFT) approach by H.-Y. Choi, A.B. Harris and E.J. Mele [Phys. Rev. B 40, 3766 (1989)], in which planar rotors (representing polymer chains) are pinned onto a rigid two-dimensional triangular lattice. Equilibrium structures and transition temperatures are in good 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.