Application of Symplectic Algorithm in the Quasi-Classical Trajectory Calculation of N+O<SUB<2</SUB< Reaction

Quasi-classical trajectories of N+O<SUB<2</SUB< reaction system have been performed by the fourth-order explicit symplectic algorithm（S4）,based on a new ground potential energy surface constructed by Sayós et al,and the results are compared with those of the fourth-order Runge-Kutta scheme（RK4）.Conclusion has been drawn that RK4 cannot conserve the total energy of N+O<SUB<2</SUB< reaction system,and the computed trajectories do not actually describe the motion of N+O<SUB<2</SUB< reaction system.However,S4 can maintain both the symplectic structure of the Hamilton system and total energy of（N+）O<SUB<2</SUB< reaction system during integration.It is revealed that that S4 exhibits more excellence than RK4 in the quasi-classical trajectory calculation of N+O<SUB<2</SUB< reaction system.