A Galerkin Radial Basis Function Method for the Schrödinger Equation

In this article, we consider the discretization of the time-dependent Schrödinger equation using radial basis functions (RBFs). We formulate the discretized problem over an unbounded domain without imposing explicit boundary conditions. Since we can show that time stability of the discretization is not guaranteed for an RBF-collocation method, we propose to employ a Galerkin ansatz instead. For Gaussians, it is shown that exponential convergence is obtained up to a point where a systematic error from the domain where no basis functions are centered takes over. The choice of the shape parameter and of the resolved region is studied numerically. Compared to the Fourier method with periodic boundary conditions, the basis functions can be centered in a smaller domain which gives increased accuracy with the same number of points.