Cost-reduction implicit exponential Runge-Kutta methods for highly oscillatory systems

In this paper, two novel classes of implicit exponential Runge-Kutta (ERK) methods are studied for solving highly oscillatory systems. Firstly, we analyze the symplectic conditions for two kinds of exponential integrators and obtain the symplectic method. In order to effectively solve highly oscillatory problems, we try to design the highly accurate implicit ERK integrators. By comparing the Taylor series of numerical solution with exact solution, it can be verified that the order conditions of two new kinds of exponential methods are identical to classical Runge-Kutta (RK) methods, which implies that using the coefficients of RK methods, some highly accurate numerical methods are directly formulated. Furthermore, we also investigate the linear stability regions for these exponential methods. Finally, numerical results not only display the long time energy preservation of the symplectic method, but also illustrate the accuracy and efficiency of these formulated methods in comparison with standard ERK methods.