Heteroclinic orbits for a higher order phase transition problem

Abstract

A standard model for one-dimensional phase transitions is the second-order semilinear equation with bistable nonlinearity, where one seeks a solution which connects the two stable values. From an Ising-like model but which includes long-range interaction, one is led to consider the equation where the second-order operator is replaced by one of arbitrarily high order. Others have found the desired heteroclinic solutions for such equations, under the assumption that the higher-order terms have small coefficients, by employing singular perturbation methods for dynamical systems. Here, without making any assumption on the sizes of the coefficients, we obtain such heteroclinic solutions by using variational methods under the assumption that the nonlinearity arises from a potential having two wells of equal depths.