Nucleation and relaxation processes in weak solutions: molecular dynamics simulation

ABSTRACT

The kinetics of homogeneous nucleation of the vapour-gas phase was studied by the molecular dynamics (MD) method in Lennard-Jones systems simulating solutions with partial (A) and complete (B) solubility of components. The calculations were carried out at a temperature close to the normal boiling point of the solvent, two concentrations of the solute, and negative pressures. The pressure, as a function of density and concentration, in stable and metastable states, the parameters of phase equilibrium at a flat interface were determined. The ultimate stretching Δp_n= p_s–p_n exceeded than those calculated from the classical nucleation theory at concentrations of solute c > 0.14 and were less theoretical ones at c < 0.2 in solutions A and B, respectively. A qualitative difference in the formation and growth of the vapour-gas nucleus in solutions A and B was established. In solution A, the partial density of the solvent sharply decreases and the density of the volatile component increases at the region of the bubble formation. In solution B, the density of the volatile component inside the bubble remains close to the density in the surrounding phase, and the density of the solvent decreases at the initial stage of bubble formation.

KEYWORDS:

• Lennard-Jones mixtures
• molecular dynamics simulation
• vapour–liquid equilibrium
• bubble nucleation
• nucleation rate

Acknowledgements

The authors are grateful to the Supercomputing Centre of the Institute of Mathematics and Mechanics of UB RAS for kindly providing the computer facilities for this work.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The investigation has been conducted at the expense of a grant of the Russian Science Foundation [project № 18-19-00276-P].