Exact estimate for the spectral function of the singular Schrödinger operator
The author studies the spectral function of the singular Schrödinger operators with a countably set of complex eigenvalues, defined on bounded three dimensional domains. In the main result of the paper it is proved that the spectral function can be expressed as a sum of two functions: one of them is explicitly defined and for the another it is given an estimate. From this it is deduced a sufficient condition of summability for the eigenfunction expansions.
summability for the eigenfunction expansions
scientific article; zbMATH DE number 4030085