A space-time DG method for the Schr\"odinger equation with variable potential

TL;DR

This paper introduces a space-time discontinuous Galerkin method for solving the Schrödinger equation with variable potential, achieving optimal convergence and computational efficiency through novel polynomial spaces.

Contribution

The paper develops a new ultra-weak DG discretization for the Schrödinger equation, including a quasi-Trefftz polynomial space that reduces degrees of freedom and handles smooth potentials.

Findings

Method is well-posed and quasi-optimal in mesh-dependent norms.

Achieves optimal h-convergence error estimates.

Numerical experiments confirm accuracy and efficiency.

Abstract

We present a space-time ultra-weak discontinuous Galerkin discretization of the linear Schr\"odinger equation with variable potential. The proposed method is well-posed and quasi-optimal in mesh-dependent norms for very general discrete spaces. Optimal $h$-convergence error estimates are derived for the method when test and trial spaces are chosen either as piecewise polynomials, or as a novel quasi-Trefftz polynomial space. The latter allows for a substantial reduction of the number of degrees of freedom and admits piecewise-smooth potentials. Several numerical experiments validate the accuracy and advantages of the proposed method.