ABSTRACT
Several methods have been suggested in the literature, which employ various trajectory guided grids of frozen Gaussian wavepackets as a basis set for quantum propagation. They exploit the same idea illustrated in Figure 20.1a, that a grid can follow the wavefunction. Therefore a basis does not have to cover the whole Hilbert space of the system, as the one shown in Figure 20.1b. Among the methods considered in this chapter are the method of variational Multiconfigurational Gaussians (vMCG) and the Gaussian Multiconfigurational time-dependent Hartree (G-MCTDH) technique [1], the method of Coupled Coherent States (CCS) [2] and the recently developed Multiconfigurational Ehrenfest approach (MCE) [3], which all differ in the exact way their grids are guided. The goal of this chapter is to present all four techniques from the same perspective and compare their mathematical structure.
