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Pal R, Jayatilaka D, Nishibori E. Structure Factors and Charge Density Description of Aluminum: A Quantum Crystallographic Study. J Phys Chem A 2022; 126:2042-2049. [PMID: 35316043 DOI: 10.1021/acs.jpca.1c10730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Static structure factors and charge density for metallic aluminum were investigated by periodic calculations using atom-centered Gaussian-type basis sets with the Perdew-Burke-Ernzerhof (PBE) functional implemented in the CRYSTAL14 package and X-ray constrained wave function (XCW) fitting. The effects of additional diffuse d and f basis functions on structure factors were compared with synchrotron powder X-ray diffraction and quantitative convergent electron beam diffraction data. Changes in structure factors from an independent atom model at 022, 113, and 222 reflections introduced d and f basis functions similar to those of the experimental data. The XCW fitting was applied to different sizes of aluminum clusters. The charge density features for a 50-atom cluster clearly demonstrated electron accumulation at tetrahedral sites and electron depletion at octahedral sites. The resolution dependence of the XCW study suggests that structure factors of the five lowest resolution reflections with 0.1% accuracy were indispensable for determining the detailed bonding description in the case of metallic aluminum.
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Affiliation(s)
- Rumpa Pal
- Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
| | - Dylan Jayatilaka
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Perth, Washington 6009, Australia
| | - Eiji Nishibori
- Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.,Tsukuba Research Center for Energy Materials Science, University of Tsukuba, Tsukuba 305-8571, Japan
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Origin of ω-phase formation in metastable β-type Ti-Mo alloys: cluster structure and stacking fault. Sci Rep 2020; 10:8664. [PMID: 32457317 PMCID: PMC7251116 DOI: 10.1038/s41598-020-65254-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 04/08/2020] [Indexed: 11/21/2022] Open
Abstract
The ω-phase formation and its collapsed structures in metastable β-type Ti-Mo alloys were illustrated by first-principles calculations and experimental evidence of a partially collapsed ω-phase in the nano-scale Mo-depleted region under a rapid cooling via high-angle annular dark-field scanning transmission electron microscopy. The ease of ω-phase formation within -Mo-Ti-Mo- poor cluster structure was not only due to the low energy barrier in the collapse pathway, which was caused by the reduced lattice distortion, but also due to the softening of the shear modulus (G111) as a result of the small charge density difference. The most stable collapsed structure of the ω-phase strongly depended on the minimum stacking fault energy among different collapse degrees in accordance to the smallest charge density difference. Therefore, the concurrent compositional and structural instabilities of the ω-phase was attributed to the coupling effect of the cluster structure with stacking fault from the atomic and electronic basis.
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Tightly binding valence electron in aluminum observed through X-ray charge density study. Sci Rep 2018; 8:11964. [PMID: 30097629 PMCID: PMC6086884 DOI: 10.1038/s41598-018-30470-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 07/31/2018] [Indexed: 11/17/2022] Open
Abstract
Accurate and high reciprocal resolution experimental structure factors of aluminum were determined from a synchrotron powder X-ray diffraction data measured at 30 K with sin θ/λ < 2.31 Å−1. The structure factors have small deviations from independent atom model in sin θ/λ < 0.83 Å−1. Theoretical structure factors were prepared using density functional theoretical calculations by full potential linearized augmented plane wave method. The deviation between experimental and theoretical data was also observed at around sin θ/λ ≈ 0.4 Å−1. The charge density was determined by an extended Hansen-Coppens multipole modeling using experimental and theoretical structure factors. Charge density maxima at tetrahedral site were observed in both experimental and theoretical deformation density. The charge-density difference peaks indicating directional bonding formation were observed in the difference density between experiment and theory. The present study reveals tight binding like character of valence electron of aluminum. The fact will provide a crucial information for development of high-performance aluminum alloy.
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Qi X, Zhou Y, Fichthorn KA. Obtaining the solid-liquid interfacial free energy via multi-scheme thermodynamic integration: Ag-ethylene glycol interfaces. J Chem Phys 2016; 145:194108. [DOI: 10.1063/1.4967521] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Affiliation(s)
- Xin Qi
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Ya Zhou
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Kristen A. Fichthorn
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Jones TE, Rocha TCR, Knop-Gericke A, Stampfl C, Schlögl R, Piccinin S. Adsorbate induced vacancy formation on silver surfaces. Phys Chem Chem Phys 2014; 16:9002-14. [DOI: 10.1039/c4cp00778f] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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6
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Wang W, Shang S, Wang Y, Darling K, Mathaudhu S, Hui X, Liu Z. Electron localization morphology of the stacking faults in Mg: A first-principles study. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2012.09.028] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Yuasa M, Nishihara D, Mabuchi M, Chino Y. Hydrogen embrittlement in a magnesium grain boundary: a first-principles study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:085701. [PMID: 22277378 DOI: 10.1088/0953-8984/24/8/085701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
First-principles fully relaxed tensile and shear test simulations were performed on Σ10(1124)/[1100] tilt Mg grain boundary (GB) models, with and without H segregation, to investigate mechanisms of H embrittlement of Mg. Strengthening as a result of covalent-like characteristics of Mg-H bonds prevailed over weakening of Mg-Mg bonds resulting from charge transfer; as a result, an H atom strengthened the GB. In addition, because the strong Mg-H bonds suppressed macroscopic GB fracture, elongation to failure was not reduced by H segregation. However, the resistance to GB shearing was increased by H segregation. It is therefore suggested that H segregation enhances crack growth at the GB, because dislocation emission from the crack tip is suppressed, resulting in H embrittlement of Mg.
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Affiliation(s)
- Motohiro Yuasa
- Department of Energy Science and Technology, Graduate School of Energy Science, Kyoto University, Sakyo-ku, Kyoto, Japan
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Abstract
Aluminum is considered to approach an "ideal" metal or free electron gas. The valence electrons move freely, as if unaffected by the presence of the metal ions. Therefore, the electron redistribution due to chemical bonding is subtle and has proven extremely difficult to determine. Experimental measurements and ab initio calculations have yielded substantially different results. We applied quantitative convergent-beam electron diffraction to aluminum to provide an experimental determination of the bonding electron distribution. Calculation of the electron distribution based on density functional theory is shown to be in close agreement. Our results yield an accurate quantitative correlation between the anisotropic elastic properties of aluminum and the bonding electron and electrostatic potential distributions.
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Affiliation(s)
- Philip N H Nakashima
- ARC Centre of Excellence for Design in Light Metals, Monash University, Victoria 3800, Australia.
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Goel T, Patra CN, Mukherjee T, Chakravarty C. Excess entropy scaling of transport properties of Lennard-Jones chains. J Chem Phys 2008; 129:164904. [DOI: 10.1063/1.2995990] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Riggleman RA, de Pablo JJ. Antiplasticization and local elastic constants in trehalose and glycerol mixtures. J Chem Phys 2008; 128:224504. [DOI: 10.1063/1.2925684] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Sung BJ, Yethiraj A. The effect of matrix structure on the diffusion of fluids in porous media. J Chem Phys 2008; 128:054702. [PMID: 18266457 DOI: 10.1063/1.2823735] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The effect of matrix structure on the transport properties of adsorbed fluids is studied using computer simulations and percolation theory. The model system consists of a fluid of hard spheres diffusing in a matrix of hard spheres fixed in space. Three different arrangements of the fixed spheres, random, templated, and polymeric, are investigated. For a given matrix volume fraction the diffusion coefficient of the fluid, D, is sensitive to the manner in which the matrix is constructed, with large differences between the three types of matrices. The matrix is mapped onto an effective lattice composed of vertices and bonds using a Voronoi tessellation method where the connectivity of bonds is determined using a geometric criterion, i.e., a bond is connected if a fluid particle can pass directly between the two pores the bond connects, and disconnected otherwise. The percolation threshold is then determined from the connectivity of the bonds. D displays universal scaling behavior in the reduced volume fraction, i.e., D approximately (1-phi(m)phi(c))(gamma), where phi(m) is the matrix volume fraction and phi(c) is the matrix volume fraction at the percolation threshold. We find that gamma approximately 2.2, independent of matrix type, which is different from the result gamma approximately 1.53 for diffusion in lattice models, but similar to that for conduction in Swiss cheese models. Lattice simulations with biased hopping probabilities are consistent with the continuous-space simulations, and this shows that the universal behavior of diffusion is sensitive to details of local dynamics.
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Affiliation(s)
- Bong June Sung
- Department of Chemistry, Sogang University, Seoul 121-742, Republic of Korea
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Jones TE, Eberhart ME, Clougherty DP. Topology of the spin-polarized charge density in bcc and fcc iron. PHYSICAL REVIEW LETTERS 2008; 100:017208. [PMID: 18232817 DOI: 10.1103/physrevlett.100.017208] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Indexed: 05/25/2023]
Abstract
We report the first investigation of the topology of spin-polarized charge density, specifically in bcc and fcc iron. While the total spin-density is found to possess the topology of the non-magnetic prototypical structures, the spin-polarized charge densities of bcc and high-spin fcc iron are atypical. In these cases, the two spin densities are correlated: the spin-minority electrons have directional bond paths and deep minima, while the spin-majority electrons fill these holes, reducing bond directionality. The presence of distinct spin topologies allows us to show that the two phase changes seen in fcc iron (paramagnetic to low-spin and low-spin to high-spin) are different. The former follows the Landau symmetry-breaking paradigm and proceeds without a topological transformation, while the latter involves a topological catastrophe.
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Affiliation(s)
- Travis E Jones
- Molecular Theory Group, Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401, USA.
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Riggleman RA, Douglas JF, de Pablo JJ. Tuning polymer melt fragility with antiplasticizer additives. J Chem Phys 2007; 126:234903. [PMID: 17600442 DOI: 10.1063/1.2742382] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A polymer-diluent model exhibiting antiplasticization has been developed and characterized by molecular dynamics simulations. Antiplasticizer molecules are shown to decrease the glass transition temperature Tg but to increase the elastic moduli of the polymeric material in the low-temperature glass state. Moreover, the addition of antiplasticizing particles renders the polymer melt a stronger glass-forming material as determined by changes in the characteristic temperatures of glass formation, the fragility parameter D from fits to the Vogel-Folcher-Tamman-Hesse equation, and through the observation of the temperature dependence of the size of cooperatively rearranging regions (strings) in each system. The length of the strings exhibits a weaker temperature dependence in the antiplasticized glass-forming system than in the more fragile pure polymer, consistent with the Adam-Gibbs model of glass formation. Unexpectedly, the strings become increasingly concentrated in the antiplasticizer particles upon cooling. Finally, we discuss several structural indicators of cooperative dynamics, and find that the dynamic propensity (local Debye-Waller factor <u2>p) does seem to provide a strong correlation with local molecular displacements at long times. The authors also consider maps of the propensity, and find that the antiplasticized system exhibits larger fluctuations over smaller length scales compared to the pure polymer.
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Affiliation(s)
- Robert A Riggleman
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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Krekelberg WP, Ganesan V, Truskett TM. Model for the free-volume distributions of equilibrium fluids. J Chem Phys 2006; 124:214502. [PMID: 16774418 DOI: 10.1063/1.2202354] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We introduce and test via molecular simulation a simple model for predicting the manner in which interparticle interactions and thermodynamic conditions impact the single-particle free-volume distributions of equilibrium fluids. The model suggests a scaling relationship for the density-dependent behavior of the hard-sphere system. It also predicts how the second virial coefficients of fluids with short-range attractions affect their free-volume distributions.
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Affiliation(s)
- William P Krekelberg
- Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA.
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15
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Černý M, Boyer R, Šob M, Yip S. Higher-energy Structures and Stability of Cu and Al Crystals Along Displacive Transformation Paths. ACTA ACUST UNITED AC 2006. [DOI: 10.1007/s10820-005-2086-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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16
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Dudowicz J, Freed KF, Douglas JF. Entropy theory of polymer glass formation revisited. I. General formulation. J Chem Phys 2006; 124:64901. [PMID: 16483238 DOI: 10.1063/1.2166391] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A generalized entropy theory of glass formation is developed by merging the lattice cluster theory for the thermodynamics of semiflexible polymer melts at constant pressure with the Adam-Gibbs relation between the structural relaxation time and the configurational entropy. Since experimental studies have suggested that the relative rigidity of the chain backbone and the side groups is an essential parameter governing the nature of glass formation in polymers, we incorporate this rigidity disparity parameter, along with monomer structure, into our new theoretical description of the polymer fluid thermodynamics. Our entropy theory is compared with alternative theories that describe the rate of structural relaxation in glass-forming liquids in terms of an activated rate process.
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Affiliation(s)
- Jacek Dudowicz
- The James Franck Institute, The University of Chicago, Illinois 60637, USA.
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Dirama TE, Carri GA, Sokolov AP. Coupling between lysozyme and glycerol dynamics: Microscopic insights from molecular-dynamics simulations. J Chem Phys 2005; 122:244910. [PMID: 16035819 DOI: 10.1063/1.1938191] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We explore possible molecular mechanisms behind the coupling of protein and solvent dynamics using atomistic molecular-dynamics simulations. For this purpose, we analyze the model protein lysozyme in glycerol, a well-known protein-preserving agent. We find that the dynamics of the hydrogen bond network between the solvent molecules in the first shell and the surface residues of the protein controls the structural relaxation (dynamics) of the whole protein. Specifically, we find a power-law relationship between the relaxation time of the aforementioned hydrogen bond network and the structural relaxation time of the protein obtained from the incoherent intermediate scattering function. We demonstrate that the relationship between the dynamics of the hydrogen bonds and the dynamics of the protein appears also in the dynamic transition temperature of the protein. A study of the dynamics of glycerol as a function of the distance from the surface of the protein indicates that the viscosity seen by the protein is not the one of the bulk solvent. The presence of the protein suppresses the dynamics of the surrounding solvent. This implies that the protein sees an effective viscosity higher than the one of the bulk solvent. We also found significant differences in the dynamics of surface and core residues of the protein. The former is found to follow the dynamics of the solvent more closely than the latter. These results allowed us to propose a molecular mechanism for the coupling of the solvent-protein dynamics.
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Affiliation(s)
- Taner E Dirama
- Department of Polymer Science, The University of Akron, Ohio 44325, USA
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Jain TS, de Pablo JJ. Role of local structure on motions on the potential energy landscape for a model supercooled polymer. J Chem Phys 2005; 122:174515. [PMID: 15910053 DOI: 10.1063/1.1888505] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have conducted detailed Monte Carlo and molecular dynamics simulations of a model glass forming polymeric system near its apparent glass transition temperature. We have characterized the local structure of the glass using a Voronoi-Delaunay analysis of local particle arrangements. After a perturbative face elimination, we find that a significant fraction of Voronoi polyhedra consist of 12 pentagonal faces, a sign of icosahedral ordering. Further, we have identified metabasins of particle vibrations on the potential energy landscape on the basis of persistence of particle positions and neighbors over a simulated trajectory. We find that the residence times for vibrations are correlated with a particular Voronoi volume and number of neighbors of a particle; the largest metabasins correspond to particles whose average Voronoi volume is close to the value expected on the basis of the density, and whose approximate number of neighbors is close to 12. The local distortion around a particle, measured in terms of the tetrahedricity of the Delaunay simplices, reveals that the particles with a higher degree of local distortion are likely to transition faster to a neighboring metabasin. In addition to the transition between metabasins, we have also examined the influence of vibrations at inherent structures (IS) on the local structure, and find that the the low frequency modes at the IS exhibit the greatest curvature with respect to the local structure. We believe that these results establish an important connection between the local structure of glass formers and the activated dynamics, thereby providing insights into the origins of dynamic heterogeneities.
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Affiliation(s)
- Tushar S Jain
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 53706, USA
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Witkoskie JB, Cao J. Scaling and universality of inherent structure simulations. Phys Rev E 2004; 69:061108. [PMID: 15244541 DOI: 10.1103/physreve.69.061108] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2003] [Indexed: 11/07/2022]
Abstract
In this paper we explore the inherent structures (IS) approach to the dynamics of the East constrained kinetic Ising model. The inherent structures do not capture the nature of the dynamics of many quantities, including the spin autocorrelation function. Simply monitoring the quenched energy fluctuations, i.e., IS energy, results in an oversimplified single order-parameter description of the system's dynamics, but examining other features, such as domain dynamics or normal modes, may give a more complete and useful picture of the dynamics. The universality in the behavior of the IS energy of this model does not reveal nonuniversal features of the kinetics that determine long-time relaxation of the system. As a result, popular functional forms, such as the stretched exponential relaxation or Gaussian distribution of energies, may be a numerical fit to data with little physical justification. Filtering data can be shown to erase features of the system and the resulting quantities resemble more universal functional forms that lack physical insight. These results for the East model have implications for IS simulations of realistic systems and suggest careful analysis including the examination of other potential order parameters is necessary to evaluate the validity of applications of universal and scaling arguments to IS simulations.
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Affiliation(s)
- James B Witkoskie
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Sheng HW, Ma E. Atomic packing of the inherent structure of simple liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2004; 69:062202. [PMID: 15244642 DOI: 10.1103/physreve.69.062202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2003] [Indexed: 05/24/2023]
Abstract
We report a universal inherent packing structure underlying the simple liquids, the normalized distribution functions of which are independent of temperature and density. The inherent packing state, carrying the maximized configurational entropy, has intrinsic connections with the maximally random jammed state of hard spheres.
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Affiliation(s)
- H W Sheng
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA.
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Abstract
Although aluminum has a smaller modulus in [111]<112> shear than that of copper, we find by first-principles calculation that its ideal shear strength is larger because of a more extended deformation range before softening. This fundamental behavior, along with an abnormally high intrinsic stacking fault energy and a different orientation dependence on pressure hardening, are traced to the directional nature of its bonding. By a comparative analysis of ion relaxations and valence charge redistributions in aluminum and copper, we arrive at contrasting descriptions of bonding characteristics in these two metals that can explain their relative strength and deformation behavior.
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Affiliation(s)
- Shigenobu Ogata
- Department of Nuclear Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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