Existence and Stability of Klein–Gordon Breathers in the Small-Amplitude Limit

We consider a discrete Klein–Gordon (dKG) equation on in the limit of the discrete nonlinear Schrödinger (dNLS) equation, for which small-amplitude breathers have precise scaling with respect to the small coupling strength 𝜖. By using the classical Lyapunov–Schmidt method, we show existence and linear stability of the KG breather from existence and linear stability of the corresponding dNLS soliton. Nonlinear stability, for an exponentially …