Synthetic Metals, 1 7 (1987) 99- 105 9 9 IMPURITIES AND NONLINEAR DYNAMICS IN MODELS OF CONJUGATED POLYMERS D. BAERISWYL ETH-HSnggerberg, CH-8093 Zfirich (Switzerland) A. R. BISHOP Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (U.S.A.) B. HOROVITZ Physics Dept., Ben-Gurion University, Beer Sheva 84105 (Israel) S. R. PHILLPOT Xerox Webster Research Center, Webster, NY 14580 (U.S.A.) ABSTRACT We describe adiabatic statics and dynamics for electron-phonon coupled models of several linear conjugated polymers, including trans- and cis-polyacetylene, ordered A-B alloys, and site- and bond-defected systems. The ubiquitous role of "breathers" is emphasized, as well as striking renormalizations of intragap localized electronic levels. I. INTRODUCTION We have studied static and dynamic nonlinear effects in discrete, adiabatic models of several linear conjugated polymers. For trans-polyacetylene ((CH)x) we have used the familiar "SSH" tight-binding Hamiltonian (see [I]) + HSSH = ~ ~ u2 +n IK (Un-Un+l)2 + [-to + ~(Un-Un+l)](CnCn+l + C++ICn ) n (1) Here, all parameters have their usual meanings (see [I]). To model the breaking of ground state degeneracy in, e.g., cis-(CH)x polypyrroles, poly(para)phenylenes, we add to HSS H "n Hci s = t I 7- (-1)n (CnCn+ 1 + C +ICn ) , o_rrt3 ~ (C Cn+ 3 + C +3Cn ) (2a,b) n n even To represent an ordered A-B alloy, we follow [2] and add to HSS H HAB = ~ ~ ( - 1 ) n C~C n (3) n 0379-6779/87/$3.50 © Elsevier Sequoia/Printed in The Netherlands