(659d) Free Energy Calculations Along Entropic Pathways: Application to Capillary Phase Transitions
AIChE Annual Meeting
2019 AIChE Annual Meeting
Computational Molecular Science and Engineering Forum
Recent Advances in Interfacial and Nano Particle Simulation Methods
Thursday, November 14, 2019 - 9:00am to 9:15am
We analyze the capillary condensation and evaporation processes in fluids confined in a cylindrical nanopore. For this purpose, we define the entropy of the adsorbed fluid as a reaction coordinate and determine the free energy associated with both processes along entropic pathways. For capillary condensation, we identify a complex free energy profile resulting from the multi-stage nature of this phenomenon. We find capillary condensation to proceed through the nucleation of a liquid bridge across the nanopore, followed by its expansion throughout the pore to give rise to the stable phase of high density. In the case of capillary evaporation, the free energy profile along the entropy pathway also exhibits different regimes, corresponding to the initial destabilization of the layered structure of the fluid followed by the formation, and subsequent expansion, of a bubble across the nanopore.