This talk will show how several forms of equations for quantum propagation based on Frozen Gaussian basis sets can be derived from a variational principle in Lagrangian form. Among them are the known methods of Coupled Coherent States (CCS) and Gaussian-based Multiconfigurational Time Dependent Hartree (G-MCTDH), as well as a new approach named as Coupled Coherent States Trajectories (CCST). A remarkable feature of the present work is that classical motion and oscillations of quantum amplitudes are treated on the same footing. |