Abstract: Symplectic Fourier pseudo-spectral integrators for Klein-Gordon-Schrödinger equations(KGS) are investigated.A Hamiltonian formulation is presented.Fourier pseudo-spectral discretization is applied to the space approximation which leads to a finite-dimensional Hamiltonian system.Symplectic integrators,including Störmer/Verlet method and midpoint rule,are adopted in the time direction which leads to symplectic integrators for KGS.It suggests that the Störmer/Verlet method is explicit which can be coded effciently,and the midpoint rule captures mass of the original system exactly.Numerical experiments show that symplectic integrator can simulate various solitary well over a long period.

Key words: KGS equation, Fourier pseudo-spectral method, Störmer/Verlet method, midpoint rule, symplectic integrator