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

Entropy ◽  
2021 ◽  
Vol 23 (9) ◽  
pp. 1171
Author(s):  
Premkumar Leishangthem ◽  
Faizyab Ahmad ◽  
Shankar P. Das
Keyword(s):  
Density Functional ◽  
Particle System ◽  
Excess Entropy ◽  
Functional Model ◽  
Amorphous Solid ◽  
Coarse Grained ◽  
Elastic Response ◽  
Additional Contribution ◽  
Vibrational States ◽  
Coarse Grained Model

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.

scholarly journals Classical density functional theory & simulations on a coarse-grained model of aromatic ionic liquids

Soft Matter ◽  
2014 ◽  
Vol 10 (18) ◽  
pp. 3229 ◽  
Author(s):  
Martin Turesson ◽  
Ryan Szparaga ◽  
Ke Ma ◽  
Clifford E. Woodward ◽  
Jan Forsman
Keyword(s):  
Density Functional Theory ◽  
Ionic Liquids ◽  
Density Functional ◽  
Coarse Grained ◽  
Functional Theory ◽  
Coarse Grained Model

scholarly journals The Effect of Enzymatic Crosslink Degradation on the Mechanics of the Anterior Cruciate Ligament: A Hybrid Multi-Domain Model

2021 ◽  
Vol 11 (18) ◽  
pp. 8580
Author(s):  
Fadi Al Khatib ◽  
Afif Gouissem ◽  
Armin Eilaghi ◽  
Malek Adouni
Keyword(s):  
Cruciate Ligament ◽  
Three Dimensional ◽  
Domain Model ◽  
Coarse Grained ◽  
Elastic Response ◽  
Type I ◽  
Coarse Grained Model ◽  
Promising Tool ◽  
Collagen Molecules ◽  
Anterior Cruciate

The anterior cruciate ligament’s (ACL) mechanics is an important factor governing the ligament’s integrity and, hence, the knee joint’s response. Despite many investigations in this area, the cause and effect of injuries remain unclear or unknown. This may be due to the complexity of the direct link between macro- and micro-scale damage mechanisms. In the first part of this investigation, a three-dimensional coarse-grained model of collagen fibril (type I) was developed using a bottom-up approach to investigate deformation mechanisms under tensile testing. The output of this molecular level was used later to calibrate the parameters of a hierarchical multi-scale fibril-reinforced hyper-elastoplastic model of the ACL. Our model enabled us to determine the mechanical behavior of the ACL as a function of the basic response of the collagen molecules. Modeled elastic response and damage distribution were in good agreement with the reported measurements and computational investigations. Our results suggest that degradation of crosslink content dictates the loss of the stiffness of the fibrils and, hence, damage to the ACL. Therefore, the proposed computational frame is a promising tool that will allow new insights into the biomechanics of the ACL.

scholarly journals Coarse-Grained Modelling and Temperature Effect on the Morphology of PS-b-PI Copolymer

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1008 ◽  
Author(s):  
Natthiti Chiangraeng ◽  
Vannajan Sanghiran Lee ◽  
Piyarat Nimmanpipug
Keyword(s):  
Density Functional ◽  
Spatial Organization ◽  
Mean Field ◽  
Md Simulations ◽  
Coarse Grained ◽  
Functional Theory ◽  
Coarse Grained Model ◽  
Mesoscopic Models ◽  
Aggregate Morphology ◽  
Mesoscopic Simulations

Spontaneous spatial organization behavior and the aggregate morphology of polystyrene-block-polyisoprene (PS-b-PI) copolymer were investigated. Molecular dynamic (MD) and mesoscopic simulations using the dynamic of mean field density functional theory (DDF) were adopted to investigate the morphology changes exhibited by this block copolymer (BCP). In the mesoscopic simulations, several atoms in repeating units were grouped together into a bead representing styrene or isoprene segments as a coarse-grained model. Inter-bead interactions and essential parameters for mesoscopic models were optimized from MD simulations. Study indicated that morphology alternations can be induced in this system at annealing temperature of 393, 493, and 533 K. From our simulations, lamellar, bicontinuous, and hexagonally packed cylindrical equilibrium morphologies were achieved. Our simulated morphologies agree well with the reported experimental evidence at the selected temperature. The process of aggregate formation and morphology evolution were concretely clarified.

scholarly journals Study of Anharmonicity in Zirconium Hydrides Using Inelastic Neutron Scattering and Ab-Initio Computer Modeling

Inorganics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 29
Author(s):  
Jiayong Zhang ◽  
Yongqiang Cheng ◽  
Alexander I. Kolesnikov ◽  
Jerry Bernholc ◽  
Wenchang Lu ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Excited States ◽  
Lattice Dynamics ◽  
Density Functional ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Vibrational States ◽  
Functional Theory ◽  
Hydrogen Deuterium ◽  
Zirconium Hydrides

The anharmonic phonon behavior in zirconium hydrides and deuterides, including ϵ-ZrH2, γ-ZrH, and γ-ZrD, has been investigated from aspects of inelastic neutron scattering (INS) and lattice dynamics calculations within the framework of density functional theory (DFT). The harmonic model failed to reproduce the spectral features observed in the experimental data, indicating the existence of anharmonicity in those materials and the necessity of further explanations. Here, we present a detailed study on the anharmonicity in zirconium hydrides/deuterides by exploring the 2D potential energy surface of hydrogen/deuterium atoms and solving the corresponding 2D single-particle Schrödinger equation to obtain the eigenfrequencies, which are then convoluted with the instrument resolution. The convoluted INS spectra qualitatively describe the anharmonic peaks in the experimental INS spectra and demonstrate that the anharmonicity originates from the deviations of hydrogen potentials from quadratic behavior in certain directions; the effects are apparent for the higher-order excited vibrational states, but small for the ground and first excited states.

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