title: Gaussian-based techniques for quantum propagation from the time-dependent variational principle: Formulation in terms of trajectories of coupled classical and quantum variables.
abstract: In this article, two coherent-state based methods of quantum propagation, namely, coupled coherent states (CCS) and Gaussian-based multiconfiguration time-dependent Hartree (G-MCTDH), are put on the same formal footing, using a derivation from a variational principle in Lagrangian form. By this approach, oscillations of the classical-like Gaussian parameters and oscillations of the quantum amplitudes are formally treated in an identical fashion. We also suggest a new approach denoted here as coupled coherent states trajectories (CCST), which completes the family of Gaussian-based methods. Using the same formalism for all related techniques allows their systematization and a straightforward comparison of their mathematical structure and cost.
authors.affiliation: School of Chemistry, University of Leeds, Leeds LS2 9JT, United Kingdom. d.shalashilin@leeds.ac.uk
authors.forename: Dmitrii V
authors.initials: DV
authors.lastname: Shalashilin
authors.forename: Irene
authors.initials: I
authors.lastname: Burghardt