SYMMETRY PROPERTIES OF FINITE FRENKEL-KONTOROVA CHAINS

We investigate the symmetry properties of finite Frenkel-Kontorova cha ins with free-end boundary conditions. A symmetry-breaking transition is found as one varies eta, the relative strength of the harmonic and substrate interactions. This transition, from a symmetric configuratio n to a configuration with broken symmetry at eta = eta(c), is characte rized by a gap in the phonon spectrum and by disorder and reflection-s ymmetry parameters, all of which display the scaling behavior (eta(c) - eta)0.5. The chains are shown to be pinned both below and above the symmetry-breaking transition.