scheme is longer than using the multi-configuration time-dependent Hartree method (MCTDH) or its multilayer generalization , although we demonstrate that calculations are indeed doable. Specifically, for the 2D + 23BM model, more than 9 days are required to obtain the full propagation with a MPI parallelization scheme on a 32 core computer (see Table ). Note that with this Smolyak scheme and since the wavepacket is known on the full sparse grid, the adiabatic populations and other adiabatic properties can be computed easily.