Solution of diffraction problems by null field and T-matrix methods with accounting for wave field analytical continuation singularities

It is shown that the correct reduction of the null field identity to integral equation requires that the surface, on which null field condition is satisfied, covers the set of singularities of diffraction field analytical continuation into interior of the scatterer. Moreover, the solution algorithm of the obtained integral equation is demonstrated to be fastest and most stable, if the above mentioned surface is constructed by analytical deformation of scatterer boundary.