Molecular dynamics simulation of supersaturated vapor nucleation in slit pore

Yasuoka, Kenji; Gao, Guangtu; Zeng, Xiao Cheng

doi:10.1063/1.480973

Cited by 47 publications

(38 citation statements)

References 24 publications

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“…We first considered a binary fluid mixture of water and argon (with 11.1% mole fraction of Ar) confined to the slit nanopore (D ¼ 0.62 nm) whose two opposing walls are smooth and hydrophobic (13)(14)(15). The fluid mixture was initially equilibrated at a constant temperature (T ¼ 1000 K) and a constant lateral pressure (p xy ¼ 500 MPa) and then subjected to an instantaneous quench to T ¼ 250 K. After 30 ns equilibration, a monolayer gas clathrate was observed, as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Guest-free monolayer clathrate and its coexistence with two-dimensional high-density ice

Bai

Angell

Zeng

2010

Proc. Natl. Acad. Sci. U.S.A.

104

127

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Three-dimensional (3D) gas clathrates are ice-like but distinguished from bulk ices by containing polyhedral nano-cages to accommodate small gas molecules. Without space filling by gas molecules, standalone 3D clathrates have not been observed to form in the laboratory, and they appear to be unstable except at negative pressure. Thus far, experimental evidence for guest-free clathrates has only been found in germanium and silicon, although guest-free hydrate clathrates have been found, in recent simulations, able to grow from cold stretched water, if first nucleated. Herein, we report simulation evidence of spontaneous formation of monolayer clathrate ice, with or without gas molecules, within hydrophobic nano-slit at low temperatures. The guest-free monolayer clathrate ice is a low-density ice (LDI) whose geometric pattern is identical to Archimedean 4 · 8 2 -truncated square tiling, i.e. a mosaic of tetragons and octagons. At large positive pressure, a second phase of 2D monolayer ice, i.e. the puckered square high-density ice (HDI) can form. The triple point of the LDI/liquid/HDI three-phase coexistence resembles that of the ice-I h ∕water∕ice-III three-phase coexistence. More interestingly, when the LDI is under a strong compression at 200 K, it transforms into the HDI via a liquid intermediate state, the first direct evidence of Ostwald's rule of stages at 2D. The tensile limit of the 2D LDI and water are close to that of bulk ice-I h and laboratory water.2D high-density ice | 2D low-density ice | 2D monolayer ice clathrate | Ostwald rule of stages | tensile limit of 2D liquid N atural gas is largely reserved in nature in the form of gas clathrates on the world's ocean floors (1-7). In the laboratory, gas clathrates can be produced by bringing a nonpolar gas in direct contact with liquid water under moderate pressure and at low temperature (1,(8)(9)(10)(11)). Since gas clathrates possess an open-cage structure to accommodate small gas molecules, gas clathrates can be characterized by two parameters: (1) the minimum gas pressure needed to stabilize the clathrates, and (2) the degree of occupancy or the fraction of cages occupied by the gas molecules. Although structural and thermodynamic properties of many gas clathrates are well characterized, the kinetic process of 3D clathrate formation is still less understood (1, 12). In an attempt to gain molecular insight into kinetics of clathrate formation, we carried out molecular dynamics (MD) simulations of clathrate formation within a slit nanopore whose width D is on the scale of 0.6 nm (see Materials and Methods). Because the slit nanopore can only accommodate one molecular layer of water, the timescale required for the formation of the quasi-2D gas clathrate is within the reach of MD simulation (typically 10-10 2 ns). Results and DiscussionsWe first considered a binary fluid mixture of water and argon (with 11.1% mole fraction of Ar) confined to the slit nanopore (D ¼ 0.62 nm) whose two opposing walls are smooth and hydrophobic (13-15). The fluid mixture was ...

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Section: Resultsmentioning

confidence: 99%

“…The TIP5P model was used for the water (42). For the smooth wall, we opted the 9-3 Lennard-Jones (LJ) potential for the water-hydrophobic wall interaction (13)(14)(15)43). The MD simulations were performed using the constant lateral pressure and constant temperature (Np xy T) ensemble.…”

Section: Methodsmentioning

confidence: 99%

Guest-free monolayer clathrate and its coexistence with two-dimensional high-density ice

Bai

Angell

Zeng

2010

Proc. Natl. Acad. Sci. U.S.A.

104

127

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“…Atomistic simulations, such as molecular dynamics and Monte Carlo simulations have provided important information on the microscopic aspects of the wetting of foreign walls by liquid and crystal [36][37][38][39]62]. Recent Monte Carlo studies revealed the importance of the line tension [36,62] in the case of unstructured walls.…”

Section: Introductionmentioning

confidence: 99%

Phase-field crystal modelling of crystal nucleation, heteroepitaxy and patterning

Gránásy

Tegze

Tóth

et al. 2011

Philosophical Magazine

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We apply a simple dynamical density functional theory, the phase-field-crystal (PFC) model, to describe homogeneous and heterogeneous crystal nucleation in 2d monodisperse colloidal systems and crystal nucleation in highly compressed Fe liquid. External periodic potentials are used to approximate inert crystalline substrates in addressing heterogeneous nucleation. In agreement with experiments in 2d colloids, the PFC model predicts that in 2d supersaturated liquids, crystalline freezing starts with homogeneous crystal nucleation without the occurrence of the hexatic phase. At extreme supersaturations crystal nucleation happens after the appearance of an amorphous precursor phase both in 2d and 3d. We demonstrate that contrary to expectations based on the classical nucleation theory, corners are not necessarily favourable places for crystal nucleation. Finally, we show that adding external potential terms to the free energy, the PFC theory can be used to model colloid patterning experiments.

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“…Note that we do not discuss here the inverse process (nucleation of fluid droplets from the vapor in confined systems, see e.g. [42,43]), and we consider neither the structure (and possible rupture) of non-volatile confined liquid bridges [44,45], nor liquid-vapor systems confined by patterned surfaces (see e.g. [44][45][46][47].…”

Section: Introductionmentioning

confidence: 99%

Molecular-dynamics simulation of evaporation processes of fluid bridges confined in slitlike pores

2009

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A simple fluid, described by point-like particles interacting via the Lennard-Jones potential, is considered under confinement in a slit geometry between two walls at distance Lz apart for densities inside the vapor-liquid coexistence curve. Equilibrium then requires the coexistence of a liquid "bridge" between the two walls, and vapor in the remaining pore volume. We study this equilibrium for several choices of the wall-fluid interaction (corresponding to the full range from complete wetting to complete drying, for a macroscopically thick film), and consider also the kinetics of state changes in such a system. In particular, we study how this equilibrium is established by diffusion processes, when a liquid is inserted into an initially empty capillary (partial or complete evaporation into vacuum), or when the volume available for the vapor phase increases. We compare the diffusion constants describing the rates of these processes in such inhomogeneous systems to the diffusion constants in the corresponding bulk liquid and vapor phases.

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Molecular dynamics simulation of supersaturated vapor nucleation in slit pore

Cited by 47 publications

References 24 publications

Guest-free monolayer clathrate and its coexistence with two-dimensional high-density ice

Guest-free monolayer clathrate and its coexistence with two-dimensional high-density ice

Phase-field crystal modelling of crystal nucleation, heteroepitaxy and patterning

Molecular-dynamics simulation of evaporation processes of fluid bridges confined in slitlike pores

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