On Influence of Intensive Stationary Electromagnetic Field on the   Behavior of Fermionic Systems
  Exact solutions of Schroedinger and Pauli equations for charged particles in an external stationary electromagnetic field of an arbitrary configuration are constructed. Green functions of scalar and spinor particles are calculated in this field. The corresponding equations for complex energy of particles bounded by short range potential are deduced. Boundary condition typical for delta - potential is not used in the treatment. Explicit analytical expressions are given for the shift and width of a quasistationary level for different configurations of the external field. The critical value of electric field in which the idea of quasistationary level becomes meaningless is calculated. It is shown that the common view on the stabilizing role of magnetic field concerns only scalar particles. 
V.N. Rodionov and A.M. Mandel and E.V. Arbuzova