Domain Wall and Periodic Solutions of a Coupled phi6 Model

Coupled triple well (phi6) one-dimensional potentials occur in both condensed matter physics and field theory. Here we provide a set of exact periodic solutions in terms of elliptic functions (domain wall arrays) and obtain single domain wall solutions in specific limits. Both topological, nontopological (e.g. some pulse-like solutions) as well as mixed domain walls are obtained. We relate these solutions to structural phase transitions in materials with polarization, shuffle modes and strain. We calculate the energy and the asymptotic interaction between solitons for various solutions. We also consider the discrete analog of these coupled models and obtain several single and periodic domain wall exact solutions.