Green's function and scattering matrix in a discrete oscillator basis

Convenient analytic finite-dimensional approximations for basic operators of scattering theory-specifically, the Green's function and the off-shell T matrix—are constructed in an oscillator basis for real-and complex-valued local and nonlocal interaction potentials. It is shown that the approximate operators converge smoothly to their exact counterparts as the dimensions of the oscillator basis are increased step by step. The simple and rather accurate formulas obtained in this study can be widely used in various applications of quantum scattering theory.