Molecular simulation study of effect of molecular association on vapor-liquid interfacial properties

Singh, Jayant K.; Kofke, David A.

doi:10.1063/1.1808118

Cited by 30 publications

(35 citation statements)

References 36 publications

(23 reference statements)

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“…While the majority of the work has been done on planar surfaces, Bohlen and Schoen [30] studied the prewetting transitions on nonplanar surfaces. In recent years with the development of advanced methodologies such as GC-TMMC [31], it is more feasible to investigate the first-order phase transition [32][33][34] including the prewetting transition, as shown by Errington and co-workers for model argon on solid carbon surface [16,17]. Compared with Monte Carlo techniques, molecular dynamics (MD) is less utilized to predict the prewetting transition; nonetheless in conjunction with Monte Carlo techniques; MD is very useful to predict boundary tension, as shown in previous work [18].…”

Section: Introductionmentioning

confidence: 99%

Quasi-2D and prewetting transitions of square-well fluids on a square-well substrate

Saha

Singh

et al. 2009

Molecular Physics

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Molecular simulation methodologies are employed to study the first-order transition of variable square-well (SW) fluids on a wide range of weak attractive surfaces. Surface phase diagram of SW fluids of attractive well diameter ff ¼ 1.5, 1.75, 2.0 on a smooth, structureless surface modelled by a SW potential is reported via grand-canonical transition-matrix Monte Carlo (GC-TMMC) and histogram reweighting techniques. Fluids with ff ¼ 1.5 and 1.75 show quasi-2D vapour-liquid phase transition; on the other hand, prewetting transition is visible for a SW fluid with larger well-extent ff ¼ 2.0. The prewetting line, its length, and closeness to the bulk saturation curve are found to depend strongly on the nature of the fluid-fluid and fluid-wall interaction potentials. Boundary tension of surface coexistence films is calculated by two methods. First, the finite size scaling approach of Binder is used to evaluate the boundary tension via GC-TMMC. Second, the results of the boundary tension are verified by virtue of its relation to the pressure tensor components, which are calculated using a NVT-Monte Carlo approach. The results from the two methods are in good agreement. Boundary tension is found to increase with the increase in the wall-fluid interaction range for the quasi-2D system; conversely, boundary tension for thinthick film, at prewetting transition, decreases with the increase in the wall-fluid interaction range.

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Section: Introductionmentioning

confidence: 99%

Quasi-2D and prewetting transitions of square-well fluids on a square-well substrate

Saha

Singh

et al. 2009

Molecular Physics

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“…The method enables one to evaluate the infinite-system interfacial tension by extrapolating a series of finite-system interfacial free energies. GC-TMMC has been applied recently for variety of systems, 29,[49][50][51][52][53][54] mainly due to the ease of utilizing parallel processors and efficiency over GEMC. 55 In this work, we applied GC-TMMC to evaluate the phase coexistence data of variable SW fluid of interaction range = 1.25, 1.75, 2.0, and 3.0.…”

Section: ͑12͒mentioning

confidence: 99%

Vapor-liquid critical and interfacial properties of square-well fluids in slit pores

Jana

Singh

Kwak

2009

The Journal of Chemical Physics

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Computer simulation studies of a square-well fluid in a slit pore. Spreading pressure and vapor-liquid phase equilibria using the virtual-parameter-variation method J. Chem. Phys. 112, 5168 (2000) Vapor-liquid phase equilibria of square-well ͑SW͒ fluids of variable interaction range: = 1.25, 1.75, 2.0, and 3.0 in hard slit pores are studied by means of grand-canonical transition-matrix Monte Carlo ͑GC-TMMC͒ simulation. Critical density under confinement shows an oscillatory behavior as slit width, H, reduced from 12 to 1 . Two linear regimes are found for the shift in the critical temperature with the inverse in the slit width. The first regime is seen for H Ͼ 2.0 with linear increase in the slope of shift in the critical temperature against inverse slit width with increasing interaction range. Subsequent decrease in H has little consequence on the critical temperature and it remains almost constant. Vapor-liquid surface tensions of SW fluids of variable well extent in a planar slit pore of variable slit width are also reported. GC-TMMC results are compared with that from slab based canonical Monte Carlo and molecular dynamics techniques and found to be in good agreement. Although, vapor-liquid surface tension under confinement is found to be lower than the bulk surface tension, the behavior of surface tension as a function of temperature is invariant with the variable pore size. Interfacial width, , calculated using a hyperbolic function increases with decreasing slit width at a given temperature, which is contrary to what is being observed recently for cylindrical pores. Inverse scaled interfacial width ͑ / H͒, however, linearly increases with increase in the scaled temperature ͑T c,bulk − T͒ / T c,bulk .

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“…However, the change in thick film density with increasing associating strength is quite noticeably even in a lower association range (" af 4 0) for two-site and four-site associating fluids. As the sites are located opposite to each other in the case of a two-site associating fluid, the thick film should contain linear chain clusters, as seen from the bulk liquid phase for a square-well-based associating fluid [33], and hence the reason for the enhancement in the thick film density compared with that for a one-site associating fluid with increasing associating strength. Decreasing temperature promotes two-site molecules to organize with the propensity to form a chain structure, allowing the thick film to thicken.…”

Section: Molecular Physics 1243mentioning

confidence: 98%

“…Khan et al performed in a grand-canonical ensemble at a constant chemical potential , volume V, and temperature T. In this work, four basic Monte Carlo (MC) moves are used, namely displacement, insertion and deletion, and rotation moves [33] to sample the entire phase space efficiently. The probability distribution among different density states is evaluated from the microscopic transition probability which is updated during different moves in matrix form.…”

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confidence: 99%

Surface phase transitions of multiple-site associating fluids

2012

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Surface phase transitions of Lennard-Jones (LJ) based two-and four-site associating fluids have been studied for various associating strengths using grand-canonical transition matrix Monte Carlo simulations. Our results suggest that, in the case of a smooth surface, represented by a LJ 9-3-type potential, multiple-site associating fluids display a prewetting transition within a certain temperature range. However, the range of the prewetting transition decreases with increasing associating strength and increasing number of sites on the fluid molecules. With the addition of associating sites on the surface, a quasi-2D vapor-liquid transition may appear, which is observed at a higher surface site density for weaker associating fluids. The prewetting transition at lower associating strength is found to shift towards the quasi-2D vapor-liquid transition with increasing surface site density. However, for highly associating fluids, the prewetting transition is still intact, but shifts slightly towards the lower temperature range. Adsorption isotherms, chemical potentials and density profiles are used to characterize surface phase transitions.

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Molecular simulation study of effect of molecular association on vapor-liquid interfacial properties

Cited by 30 publications

References 36 publications

Quasi-2D and prewetting transitions of square-well fluids on a square-well substrate

Quasi-2D and prewetting transitions of square-well fluids on a square-well substrate

Vapor-liquid critical and interfacial properties of square-well fluids in slit pores

Surface phase transitions of multiple-site associating fluids

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