Initial stages of salt crystal dissolution determined with ab initio molecular dynamics

Abstract

The initial stages of NaCl dissolution in liquid water have been examined with state-of-the-art ab initio molecular dynamics and free energy sampling techniques. Our simulations reveal a complex multi-step process triggered by the departure of Cl ions from the lattice, with a well-defined intermediate state wherein departing ions are partially solvated but remain in contact with the crystal. The polarizability of Cl⁻ is identified as the source of the anion's preferential initial dissolution, an effect which leads a forcefield based description of NaCl dissolution to fail to identify a preference for Cl over Na dissolution.