Dynamics of cubic-quintic nonlinear Schrödingeröequation are studied numerically with symplectic method. Behaviors of the equation are discussed with increased quintic nonlinear parameter. We observe homoclinic orbit crossing and elliptic orbit in turn and the system has recurrent solutions. Pattern drifting of solutions is also discussed. It is shown that pattern drifting can be slowed down by increasing the quintic nonlinear parameter.

An improved shooting method is applied to 1D Gross-Pitaevskii equation,which describes Bose-Einstein condensate of neutral atoms in harmonic trapping potential at zero temperature.Eigenvalues of ground state of condensates with different nonlinear coefficient are given.Interference of three condensates after removing the trapping potential is studied with symplectie method.A periodic evolution is shown.Influence of relative phase on interference of condensates is discussed.

Symplectic method is applied to solve numerically 1D time-dependent Gross-Pitaevskii equation. "Breathing" of the condensate is numerically illustrated. Interaction of two Bose-Einstein condensates is investigated as external potential is zero at t=0. Interference between two condensates is observed. Evolution of density due to interference at various relative phases is studied.

The ground state wavefunctions of dilute Bose-condensed atoms in a harmonic trap at T=0 are evaluated by a symplectic shooting method.Stability of the wavefunctions is tested,and a stable wavefunction is used as the initial input of the time-dependent Gross-Pitaevskii equation. The dynamic property of stable wavefunctions is numerically examined in two phase spaces when the harmonic potential is altered suddenly.The figures in the two phase spaces are regular even after a long time of interations.For negative nonlinear coefficients,two eigenvalues related to the same negative nonlinear coefficient are calculated,and the stability of the corresponding two wavefunctions is tested.

The dynamic properties of nonlinear Schrödinger equations are investigated numerically by using the symplectic scheme (Euler centered scheme). The dynamic behavior of cubic nonlinear Schrödinger equations with various nonlinear parameter is studied in different phase space.And the dynamic properties of cubic-quintic nonlinear Schrödinger equations are dealt with numerically by using the symplectic scheme. The dynamic behaviors of cubic-quintic nonlinear Schrödinger equations with different cubic and quintic nonlinear parameters are discussed in the phase space.It shows that the route varies with different cubic nonlinear parameters and with the increase of the quintic nonlinear parameters.