Metastable structures with modified weighted density-functional theory

Kaur, Charanbir; Das, Shankar P.

doi:10.1103/physreve.65.026123

Cited by 21 publications

(22 citation statements)

References 33 publications

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“…We obtain (17) whereĉ ij (k) ≡ dr exp(ik · r)c (2) ij (r) is the Fourier transform of the pair direct correlation function. If we assume that the time dependence of the Fourier modes followsρ i (k,t) ∝ exp[ω(k)t], we obtain [69][70][71][72] …”

Section: A Fluid Structure and Linear Stabilitymentioning

confidence: 99%

“…Wolynes and coworkers [11][12][13] developed a successful model of hardsphere glass formation based on the idea that the glass may be viewed as a system that is "frozen" onto a (random close-packed) nonperiodic lattice. This approach is based on the DFT theory for crystallization [1] and was followed up by a number of other investigations [14][15][16][17][18][19][20][21] extending and applying the method. All of these studies show that the free-energy landscape may exhibit minima corresponding to the particles becoming localized (trapped) on a nonperiodic lattice.…”

Section: Introductionmentioning

confidence: 99%

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Solidification in soft-core fluids: Disordered solids from fast solidification fronts

et al. 2014

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Using dynamical density functional theory we calculate the speed of solidification fronts advancing into a quenched two-dimensional model fluid of soft-core particles. We find that solidification fronts can advance via two different mechanisms, depending on the depth of the quench. For shallow quenches, the front propagation is via a nonlinear mechanism. For deep quenches, front propagation is governed by a linear mechanism and in this regime we are able to determine the front speed via a marginal stability analysis. We find that the density modulations generated behind the advancing front have a characteristic scale that differs from the wavelength of the density modulation in thermodynamic equilibrium, i.e., the spacing between the crystal planes in an equilibrium crystal. This leads to the subsequent development of disorder in the solids that are formed. For the onecomponent fluid, the particles are able to rearrange to form a well-ordered crystal, with few defects. However, solidification fronts in a binary mixture exhibiting crystalline phases with square and hexagonal ordering generate solids that are unable to rearrange after the passage of the solidification front and a significant amount of disorder remains in the system.

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Section: A Fluid Structure and Linear Stabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Solidification in soft-core fluids: Disordered solids from fast solidification fronts

et al. 2014

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“…The local minima of the free energy, signifying a low degree of mass localization, have been obtained for various interaction potentials. These include hard sphere interaction [ 7 , 27 ], Lennard–Jones [ 28 ], soft-sphere interaction [ 29 ], and Hertzian potentials [ 30 ]. A typical result obtained for the hard-sphere system in which the solution of the Percus–Yevick equation [ 31 ] has been used to compute the direct correlation function

, is displayed in Figure 5 .…”

Section: The Free Energy Landscapementioning

confidence: 99%

“…A class of minima corresponding to heterogeneous structures characterized by weak mass localization for low values of

is detected [ 27 ]. Close to freezing, these delocalized structures are more stable than the highly localized “hard-sphere glass”.…”

Section: Elasticity Of the Localized Statementioning

confidence: 99%

Localization, Disorder, and Entropy in a Coarse-Grained Model of the Amorphous Solid

Premkumar

Ahmad

Das

2021

Entropy

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We study the role of disorder in producing the metastable states in which the extent of mass localization is intermediate between that of a liquid and a crystal with long-range order. We estimate the corresponding entropy with the coarse-grained description of a many-particle system used in the classical density functional model. We demonstrate that intermediate localization of the particles results in a change of the entropy from what is obtained from a microscopic approach using for sharply localized vibrational modes following a Debye distribution. An additional contribution is included in the density of vibrational states g(ω) to account for this excess entropy. A corresponding peak in g(ω)/ω2 vs. frequency ω matches the characteristic boson peak seen in amorphous solids. In the present work, we also compare the shear modulus for the inhomogeneous solid having localized density profiles with the corresponding elastic response for the uniform liquid in the limit of high frequencies.

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“…Theoretical studies using landscape paradigm [19,20] of a many particle system have also been made to further understand this link. Microscopic models for the glassy state, based on either thermodynamic [21][22][23] or dynamic approach [24][25][26] simply assume the solid-like properties for the amorphous state. In the thermodynamics based formulation, the metastable states of a disordered solid are described [27,28] in terms of localized density profiles which also signify vibrational modes [28,29].…”

Section: Introductionmentioning

confidence: 99%

Correlation between kinetic fragility and Poisson's ratio from analysis of data for soft colloids

Mondal¹,

Premkumar²,

Das³

2021

Condens. Matter Phys.

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We consider the link between fragility and elasticity that follows from the analysis of the data for a set of soft colloid materials consisting of deformable spheres reported by [Mattsson et al., Nature, 2009, 462, 83]. The present work makes a quantitative analysis through an explicit definition for fragility index m in terms of density dependence, extending the corresponding formula of m for molecular systems in terms of temperature dependence. In addition, we fit the data for the high-frequency shear modulus for the respective soft-colloid to a corresponding theoretical expression for the same modulus. This expression for the elastic constant is in terms of the corresponding pair correlation function for the liquid treated as of uniform density. The pair correlation function is adjusted through a proper choice of the parameters for the two body interaction potential for the respective soft-colloid material. The nature of correlation between the fragility and Poisson ratio observed for the soft colloids is qualitatively different, as compared to the same for molecular glasses. The observed link between fragility of a metastable liquid and its elastic coefficients is a manifestation of the effects of structure of the fluid on its dynamics. The present work thus analyses the data on soft colloids and by introducing definitions from statistical mechanics obtains a correlation between kinetic fragility and Poissons's ratio for the soft material.

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Metastable structures with modified weighted density-functional theory

Cited by 21 publications

References 33 publications

Solidification in soft-core fluids: Disordered solids from fast solidification fronts

Solidification in soft-core fluids: Disordered solids from fast solidification fronts

Localization, Disorder, and Entropy in a Coarse-Grained Model of the Amorphous Solid

Correlation between kinetic fragility and Poisson's ratio from analysis of data for soft colloids

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