We apply and the time-dependent Hartree (TDH) method to the study of intramolecular dynamics in dimer systems. The HCl dimer is chosen as test case. Model calculations are performed on reduced dimensional representation of this system namely two-, three-, and four-dimensional ones. We assess the validity of different implementations of the TDH method including the account of direct correlations between coordinate pairs, and mixed quantum-classical and quantum-Gaussian wave packets treatments. The latter yields very good results compared to the fully quantal treatment.