Calculation and selective population of vibrational levels with the Multiconfiguration Time-Dependent Hartree (MCTDH) algorithm

In the context of studies of the intramolecular vibrational-energy redistribution (IVR) in molecules with the aid of the multiconfiguration time-dependent Hartree (MCTDH) method, we simulate the dynamics of the selective population of vibrational levels in H2CS in the presence of an external time-dependent field. The molecule is described by means of six valence polyspherical coordinates. The potential-energy surface (PES), the dipole moment function, and the kinetic energy are of direct-product form in these coordinates and hence perfectly adapted to MCTDH. In order to obtain the eigenstates and the corresponding transition moments of the system, recent developments of the MCTDH improved relaxation method, for which a first comprehensive description is given here, are exploited.