Though surprisingly effective, this approach is not a panacea, and in any event rather expensive to implement. We therefore also introduce an initial grid-point relaxation procedure, prior to the numerical propagation, which operates as follows. To begin with, for every calculation performed here, the initial wavepacket is Gaussian, and therefore the initial quantum force is known analytically everywhere. As discussed, grid points are distributed uniformly in C, and remain uniform over time. However, even for a Gaussian wavepacket, such a distribution does not lead to numerically exact F Q i values via Eq. ( ). The purpose of the relaxation procedure, therefore, is to shift the trajectories starting positions slightly (especially in the periphery) such that the numerically computed F Q i errors are minimized.