Virtual bound levels in a gap of the essential spectrum of the Schroedinger operator with a weakly perturbed periodic potential

Leonid Zelenko

In the space $L_2(R^d)$ we consider the Schrödinger operator $H_{\gamma }=-\Delta +V(x)\cdot +\gamma W(x)\cdot$, where $V(x)=V(x_1,x_2,\dots ,x_d)$ is a periodic function with respect to all the variab…