Characterization of fluid-solid phase transition of hard-sphere fluids in cylindrical pore via molecular dynamics simulation

Abstract

Articles you may be interested inThe isotropic-nematic phase transition of tangent hard-sphere chain fluids-Pure components J. Chem. Phys. 139, 034505 (2013) Equation of state and structure of hard-sphere fluids confined in a cylindrical hard pore were investigated at the vicinity of fluid-solid transition via molecular dynamics simulation. By constructing artificial closed-packed structures in a cylindrical pore, we explicitly capture the fluid-solid phase transition and coexistence for the pore diameters from 2.17 to 15. There exist some midpore sizes, where the phase coexistence might not exist or not clearly be observable. We found that the axial pressure including coexistence follows oscillatory behavior in different pore sizes; while the pressure tends to decrease toward the bulk value with increasing pore size, the dependence of the varying pressure on the pore size is nonmonotonic due to the substantial change of the alignment of the molecules. The freezing and melting densities corresponding to various pore sizes, which are always found to be lower than those of the bulk system, were accurately obtained with respect to the axial pressure.

Correlation lengths in quasi-one-dimensional systems via transfer matrices

“…An important theoretical feature of q1D systems is that they do not present genuine phase transitions, as long as particle interactions remain short-ranged [6,26,27]. As confinement weakens, these systems nonetheless exhibit a complex ordering behaviour characterized by relatively sharp structural crossovers [28][29][30][31][32][33][34][35][36][37]. A number of studies have shown that at finite pressure, these crossovers are accompanied with non-monotonic and non-smooth changes to the correlation length [10,38,39].…”

Direct determination of fluid-solid coexistence of square-well fluids confined in narrow cylindrical hard pores

“…In bulk, the constant pressure region ͑i.e., fluidsolid phase transition͒ is unobtainable for the hard sphere system by using the generic NVT MD simulation, however, the same method has shown its capability to capture the emergence of the phase transition for the hard sphere fluid confined in the cylindrical pore without any extra recipe in simulation technique. 15 In this study, although the occurrence of the phase transition has been assessed even with coinciding variation of calculated order parameters, we alert that one must not think of this particular phase transition as the firstorder transition without a proof of thermodynamic phase equilibria. The absence of the driving force of the phase equilibria or the discontinuity of the free energy.…”

“…Our previous study 15 indicates a strong dependence of the fluid-solid coexistence of hard sphere fluids on the pore size and it is expected that both the range of interaction and pore size have significant effects to the fluid-solid behavior. Another important factor in studying the behavior of model fluids is the structure.…”

Solid–liquid critical behavior of a cylindrically confined Lennard-Jones fluid

“…Nevertheless, there are a number of computersimulation studies demonstrating that freezing/melting may occur continuously as well as discontinuously in quasi-one-and quasi-two-dimensional systems. [10][11][12][13][14] Very recently, we have provided compelling evidence of the solid-liquid critical phenomena, and a molecular-level mechanism of the continuous melting, for a model of water confined in quasi-one-dimensional hydrophobic nanopores. 15 There remain unresolved questions as regards the solidliquid critical phenomena found in molecular simulations, and one of the important issues is what makes the intriguing phenomena possible: whether or not the orientation-dependent intermolecular interaction such as hydrogen bonding is necessary, or the external field that confines molecules in a narrow cylinder or slit is sufficient.…”