The investigation on the connection between: (1) closed NewtonÀCotes formulae of high-order, (2) trigonometrically-¯tted di®erential schemes and (3) symplectic integrators is presented in this paper. In the last decades, several one step symplectic methods were obtained based on symplectic geometry (see the appropriate literature). The investigation on multistep symplectic integrators is poor. In the present paper: (1) we study a trigonometrically-¯tted high-order closed NewtonÀCotes formula, (2) we investigate the necessary conditions in a general eightstep di®erential method to be presented as symplectic multilayer integrator, (3) we present a comparative error analysis in order to show the theoretical superiority of the present method, (4) we apply it to solve the resonance problem of the radial Schr€ odinger equation. Finally, remarks and conclusions on the e±ciency of the new developed method are given which are based on the theoretical and numerical results.