Even if the ISM remains a cold environment with only few energy available, dynamics effects cannot be neglected since the surface state may be significantly altered due to thermal energy dissipation. It is possible to carry electronic structure calculations on reduced and distorted structures that may reproduce somehow a thermally relaxed surface. Classical molecular dynamics based on a semi-empirical potential remains a method of choice to account for explicit dynamical effects and for large scale surfaces. Within the classical description of the intermolecular forces, only physisorption is accessible. This limitation can be overcome through the combination of dynamics/force field simulations and Self-consistent charge density functional tight binding (SCC-DFTB) calculations. This will be illustrated in the case of the adsorption of PAHs on crystalline and amorphous ices. We will present a complete description of PAH-ice interaction in the ground electronic state at low temperature, providing the binding energies and barrier heights necessary to the on-going improvement of astrochemical models.