Classical trajectories of a diatomic molecule system (CO) in laser fields are calculated in the symplectic scheme. The calculated results are compared with that with Runge-Kutta (R-K) approach. The vibration trajectories, phase trajectories and vibration energy of a diatomic molecule CO are analysed.

Asymptotic boundary conditions of one-dimensional atomic model in intense laser field are derived using Fourier transformation.Errors of the three asymptotic boundary conditions are analyzed.The probability distribution and the average energy for one-dimensional hydrogen atom in the intense laser field are numerically computed using the first boundary condition and the symplectic method for the linear inhomogeneous canonical equations.The results are compared with theoretic analyses.