Resolvent estimates for some classes of pseudo-differential operators

We study the continuity properties of the boundary Values of the resolvent of self-adjoint operators of the form H = H-0 + V, where H-0 is a pseudo-differential operator, while V is an operator that tends to zero at infinity in some sense. In particular, relativistic and non-relativistic Schrodinger operators, Dirac operators, and Stark effect Hamiltonian are included. Our results are optimal on the Holder-Zygmund scale.