On the spectrum of non-selfadjoint Schr\"odinger operators with compact   resolvent
  We determine the Schatten class for the compact resolvent of Dirichlet realizations, in unbounded domains, of a class of non-selfadjoint differential operators. This class consists of operators that can be obtained via analytic dilation from a Schr\"odinger operator with magnetic field and a complex electric potential. As an application, we prove, in a variety of examples motivated by Physics, that the system of generalized eigenfunctions associated with the operator is complete, or at least the existence of an infinite discrete spectrum. 
Yaniv Almog and Bernard Helffer
math-ph math.MP