Formation free energy of an i-mer at spinodal

In statistical mechanics, the formation free energy of an i-mer can be understood as the Gibbs free energy change in a system consisting of pure monomers after and prior to the formation of the i-mer. For molecules interacting via Lennard-Jones potential, we have computed the formation free energy of a Stillinger i-mer [F. H. Stillinger, J. Chem. Phys. 38, 1486 (1963)] and a ten Wolde-Frenkel (tWF) [P. R. ten Wolde and D. Frenkel, J. Chem. Phys. 109, 9901 (1998)] i-mer at spinodal at reduced temperatures from 0.7 to 1.2. It turns out that the size of a critical Stillinger i-mer remains finite and its formation free energy is on the order of k(B)T, and the size of a critical tWF i-mer remains finite and its formation free energy is even higher. This can be explained by Binder's theory [K. Binder, Phys. Rev. A 29, 341 (1984)] that for a system, when approaching spinodal, if the Ginzburg criterion is not satisfied, a gradual transition will take place from nucleation to spinodal decomposition, where the free-energy barrier height is on the order of k(B)T. Published under an exclusive license by AIP Publishing.

Automated summary

This study investigated the formation free energy of molecules interacting via Lennard-Jones potential at the critical point, revealing that the critical sizes of Stillinger i-mer and tWF i-mer remain finite, with their formation free energies on the order of k(B)T. This behavior can be explained by Binder's theory, suggesting a gradual transition from nucleation to spinodal decomposition when the Ginzburg criterion is not satisfied.