We study the long time behavior of small (in l 2 ) solutions of discrete nonlinear Schrödinger equations with potential. In particular, we are interested in the case that the corresponding discrete Schrödinger operator has exactly two eigenvalues. We show that under the nondegeneracy condition of Fermi Golden Rule, all small solutions decompose into a nonlinear bound state and dispersive wave. We further show the instability of excited states and generalized equipartition property.We are interested in the long time behavior of general small solutions of DNLS (1.1). By small solutions, we mean solutions of (1.1) with initial data u(0, ·) = u 0 ∈ l 2 with u 0 2 l 2 := n∈Z |u 0 (n)| 2 sufficiently small. Notice that by the potential V , the discrete Schrödinger operator H = −∆ + V may have eigenvalues. In this case one can show that there exist nonlinear bound states associated to the eigenvalues of H. Here, a nonlinear bound state is a solution of DNLS (1.1) with the form e −iωt φ ω (n) (see Proposition 1.4. Further, for other types of nonlinear bound states see [1]).When H has no eigenvalues, it is known that all small (in l 2 ) solutions scatter. By scattering, we mean that there exists η + ∈ l 2 s.t. the solution converges (in l 2 ) to the free solution e it∆ η + as t → ∞. For the case V ≡ 0 this was shown by Stefanov-Kevrekidis [43]. For the case V = 0, it follows from the dispersive estimate of H proved by Pelinovsky-Stefanov [37] (see also [27] and for lower power nonlinearity case, see [31]). However, we do not know an example s.t. V = 0 and −∆ + V has no eigenvalues (see section 4 and appendix of [27]).When H has one eigenvalue, it is known that all small solutions decouple into a nonlinear bound state and dispersive wave. This means that after subtracting suitable nonlinear bound state from the solution, the remainder scatters. Therefore, the solution u(t) can be expressed as