Solving the time-dependent Schrödinger equation in five dimensions

This paper discusses ways to simplify the problem of double ionization in a three-dimensional world by linearly polarized light. Symmetry reduces this problem to a five-dimensional one, and if electron spectra are not required, the calculation can be restricted to a small part of the configuration space where at least one of the electrons is close to the nucleus. In this case a mixed length-/ velocity-gauge representation seems optimal, and reduces the size of the problem such that it can be handled by a personal computer.