Exact static solutions to a translationally invariant discrete $\phi^4$ model

Abstract

For a discrete, translationally-invariant $\phi^4$ model introduced by Barashenkov {\it et al.} [Phys. Rev. E {\bf 72}, 35602R (2005)], we provide the momentum conservation law and demonstrate how the first integral of the static version of the discrete model can be constructed from a Jacobi elliptic function (JEF) solution. The first integral can be written in the form of a nonlinear map from which {\it any} static solution supported by the model can be constructed. A set of JEF solutions, including the staggered ones, is derived. We also report on the stability analysis for the static bounded solutions and exemplify the dynamical behavior of the unstable solutions. This work provides a road-map, through this illustrative example, on how to fully analyze translationally-invariant models in terms of their static problem, its first integral, their full-set of static solutions and associated conservation laws.