ABSTRACT
We consider exterior elliptic problems with coefficients stabilizing at infinity and study the critical value of the coupling constant (the coefficient at the potential) that separates operators with a discrete spectrum and those without it. The dependence of on the boundary condition and on the distance between the boundary and the support of the potential is described. The discrete spectrum of a non-symmetric operator with the FKW boundary condition (that appears in diffusion processes with traps) is also investigated.
Disclosure statement
No potential conflict of interest was reported by the author(s).