Prescribed energy connecting orbits for gradient systems

We are concerned with conservative systems q’’=∇V(q), q∈RN for a general class of potentials V∈C^1(R^N). Assuming that a given sublevel set {V≤c} splits in the disjoint union of two closed subsets V_{c−} and V_{c+}, for some c∈R, we establish the existence of bounded solutions qc to the above system with energy equal to −c whose trajectories connect V_{c−} and V_{c+}. The solutions are obtained through an energy constrained variational method, whenever mild coerciveness properties are present in the problem. The connecting orbits are classified into brake, heteroclinic or homoclinic type, depending on the behavior of ∇V on ∂V_{c± }. Next, we illustrate applications of the existence result to double-well potentials V, and for potentials associated to systems of duffing type and of multiple-pendulum type. In each of the above cases we prove some convergence results of the family of solutions (q_c).