Molecular dynamics studies of the vitreous state: Simple ionic systems and silica

Woodcock, Leslie V.; Angell, C. Austen; Cheeseman, P. A.

doi:10.1063/1.433213

Cited by 582 publications

(208 citation statements)

References 39 publications

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“…In a separate study, we have conducted an analogous set of simulations of SLOE, as modeled by a rigid-ion Born-Mayer-Huggins (BMH) potential [29]. SiO2, both in experiments and simulations, has been shown to exhibit a density maximum similar in character to that found in water [30].…”

Section: St2 P-v Isotherms At T = 390k (/X) T = 360k (V) T = 330kmentioning

confidence: 99%

Is there a second critical point in liquid water?

Stanley

Angell

Essmann

et al. 1994

Physica A: Statistical Mechanics and its Applications

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The supercooled and stretched regions of the phase diagram of simulated liquid water are investigated by calculating the equation of state of the ST2 and TIP4P pair-potentials. We find that simulated water does not display a re-entrant spinodal and that the projection of the density maximum line in the plane of pressure and temperature becomes positively sloped on stretching. The well-known anomalous behavior of supercooled water is tentatively associated with the existence of an inaccessible critical point. Evidence is presented that suggests the association of this new critical point with the transition between low density and high density amorphous solid water. We show how the observed transformation behavior of the two forms of amorphous solid water can be explained in terms of a first order phase transition, via a consideration of the limits of metastability associated with this kind of transition, and support this interpretation with simulations of the amorphous solid. We therefore propose a phase diagram which accounts for the behavior of both liquid and amorphous solid water.

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Section: St2 P-v Isotherms At T = 390k (/X) T = 360k (V) T = 330kmentioning

confidence: 99%

Is there a second critical point in liquid water?

Stanley

Angell

Essmann

et al. 1994

Physica A: Statistical Mechanics and its Applications

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show abstract

“…10 Such simulations provide an important theoretical means to study the properties of glasses, including the nature of the glass transition. However, pair potentials have intrinsic limitations for application to metallic systems.…”

Section: A Force-field and Parametersmentioning

confidence: 99%

Criteria for formation of metallic glasses: The role of atomic size ratio

Lee

Çağın

Johnson

et al. 2003

The Journal of Chemical Physics

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We consider metallic alloys of Cu*, Cu, and Cu** in which the atoms differ only in their atomic radii and examine how the size ratio affects the local orders in the alloy systems. These studies use molecular dynamics simulations in which the atomic interactions are modeled with a Sutton-Chen many-body potential. Considering rapid cooling of these binary and ternary alloys from the melt, we find three regimes defined by the magnitude of atomic size ratio ͑р1.0͒: with ͑i͒ large size ratios of 0.95Ͻр1.0, crystallization occurs; ͑ii͒ with moderate size ratios of 0.60рр0.95, a glass phase forms; and ͑iii͒ with small size ratios of Ͻ0.60, the alloy phase separates into pure phases and crystallize. From analyzing the structures of these binary and ternary alloys, we find that the liquid phase is characterized by local structures in which bonded atoms have local fivefold symmetry, which becomes more prominent as the glass phase forms. For phases that crystallize this local fivefold symmetry disappears as the long-range order of the crystalline phase dominates. The fivefold symmetry in the glass phase is mainly due to the icosahedral cluster formation. Energetically, the formation of icosahedral cluster is favored at the atomic size ratio of ϳ0.85, which is close to the at which our analyses shows the maximum in the fivefold symmetry and the number of icosahedral clusters. As decreases further, the phase separation is observed. The fivefold symmetry character and the number of icosahedral cluster shows the local minimum at this onset of the phase separation.

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“…23), implying a reversal in pressure dependence. MD simulations on SiO 2 melt (NBO/T ¼ 0) also reveal maxima in O and Si self-diffusivity on compression 5,25 .…”

mentioning

confidence: 99%

Atomistic insight into viscosity and density of silicate melts under pressure

et al. 2014

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A defining characteristic of silicate melts is the degree of polymerization (tetrahedral connectivity), which dictates viscosity and affects compressibility. While viscosity of depolymerized silicate melts increases with pressure consistent with the free-volume theory, isothermal viscosity of polymerized melts decreases with pressure up to B3-5 GPa, above which it turns over to normal (positive) pressure dependence. Here we show that the viscosity turnover in polymerized liquids corresponds to the tetrahedral packing limit, below which the structure is compressed through tightening of the inter-tetrahedral bond angle, resulting in high compressibility, continual breakup of tetrahedral connectivity and viscosity decrease with increasing pressure. Above the turnover pressure, silicon and aluminium coordination increases to allow further packing, with increasing viscosity and density. These structural responses prescribe the distribution of melt viscosity and density with depth and play an important role in magma transport in terrestrial planetary interiors.

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Molecular dynamics studies of the vitreous state: Simple ionic systems and silica

Cited by 582 publications

References 39 publications

Is there a second critical point in liquid water?

Is there a second critical point in liquid water?

Criteria for formation of metallic glasses: The role of atomic size ratio

Atomistic insight into viscosity and density of silicate melts under pressure

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