Abstract
Stationary scattering problem (when the distance r tends to infinity) and dynamical scattering problem (when the time t tends to infinity) are considered for the 3D Schr\"odinger equation. A simple interconnection between the scattering amplitude (stationary case) and scattering operator (dynamical case) is given in the paper. This result is a quantum mechanical analog of the ergodic formulas in the classical mechanics.