Efficient calculation of crystal-solution coexistence lines for aqueous electrolytes.

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Materials Science

Background:

• Electrolyte solutions are crucial in various natural and industrial systems.
• Accurate theoretical models are needed to predict their properties.
• Current simulation methods for phase diagrams can be computationally intensive.

Purpose of the Study:

• To develop a novel, efficient workflow for computing electrolyte phase diagrams.
• To apply this workflow to NaCl-water systems using molecular dynamics.
• To validate the accuracy of the new computational approach.

Main Methods:

• Utilized free-energy calculations from molecular dynamics simulations.
• Implemented a "chemical potential route" for phase diagram computation.
• Applied two parameterizations of the Madrid scaled-charge force field for NaCl-water.

Main Results:

• The novel workflow proved significantly more efficient than direct coexistence methods.
• Accurate NaCl-water phase diagrams were obtained at 1 bar (250-350 K).
• A stable hydrohalite (NaCl·2H2O) crystal phase was predicted below 250 K.

Conclusions:

• The "chemical potential route" offers a computationally efficient alternative for electrolyte phase diagram studies.
• The validated model accurately predicts NaCl-water phase behavior.
• This approach facilitates future research into hydrohalite nucleation and properties.