Computational details. Molecular dynamic (MD) simulations have been performed using the CP2K suite of programs . A double-zeta-valence plus polarization (DZVP) MOLOPT basis set is used to expand the Kohn-Sham orbitals, while the electronic structure is described within the Gaussian and Plane Waves framework (GPW) . Exchange and correlation are considered through the Perdew-Burke-Ernzerhof (PBE) functional, while Goedecker type (GTH) pseudopotentials have been used to model the interaction of valence electrons with the atomic cores.