Mass- and energy-conserving Gauss collocation methods for the nonlinear Schrodinger equation with a wave operator

A fully discrete finite element method with a Gauss collocation in time is proposed for solving the nonlinear Schrodinger equation with a wave operator in the d-dimensional torus, d is an element of{1, 2, 3}. Based on Gauss collocationmethod in time and the scalar auxiliary variable technique, the proposed method preserves both mass and energy conservations at the discrete level. Existence and uniqueness of the numerical solutions to the nonlinear algebraic system, as well as convergence to the exact solution with order O(h(p) + tau(k+1)) in the L-infinity(0, T; H-1) norm, are proved by using Schaefer's fixed point theorem without requiring any grid-ratio conditions, where (p, k) is the degree of the space-time finite elements. The Newton iterative method is applied for solving the nonlinear algebraic system. The numerical results show that the proposed method preserves discrete mass and energy conservations up to machine precision, and requires only a few Newton iterations to achieve the desired accuracy, with optimal-order convergence in the L-infinity(0, T; H-1) norm.

Automated summary

This paper proposes a fully discrete finite element method with a Gauss collocation in time to solve the nonlinear Schrödinger equation. The method, based on the scalar auxiliary variable technique, preserves mass and energy conservations at the discrete level. Numerical results show the effectiveness and good convergence of the method.