Stable Directions for Excited States of Nonlinear Schrödinger Equations

We consider nonlinear Schrödinger equations in R. Assume that the linear Hamiltonians have two bound states. For certain finite codimension subset in the space of initial data, we construct solutions converging to the excited states in both non-resonant and resonant cases. In the resonant case, the linearized operators around the excited states are non-self adjoint perturbations to some linear Hamiltonians with embedded eigenvalues. Although self-adjoint perturbation turns embedded eigenvalues into resonances, this class of non-self adjoint perturbations turn an embedded eigenvalue into two eigenvalues with the distance to the continuous spectrum given to the leading order by the Fermi golden rule. COMMUNICATIONS IN PARTIAL DIFFERENTIAL EQUATIONS Vol. 27, Nos. 11 & 12, pp. 2363–2402, 2002