We study anharmonic localization in a periodic five-atom chain with quadratic-quartic spring potential. We take advantage of reflection symmetries to eliminate the degeneracies of the harmonic chain and to find periodic orbits easily. We apply linear stability analysis to measure the frequency of phononlike disturbances in the presence of breathers, and to analyze the instabilities of breathers. We visualize the phase plane of breather motion directly, and develop a technique for exciting pinned and moving breathers. We observe long-lived breathers that move chaotically, and a global transition to chaos that prevents forming moving breathers at high energies.

• Received 27 May 1997

DOI:https://doi.org/10.1103/PhysRevE.56.3657