查看更多>>摘要：In this study， the mechanical properties of a graphene/aluminum (Gr/Al) composite under uniaxial tension and compression were investigated using molecular dynamics (MD) simulations。 Six different simulation models were used to investigate whether the addition of graphene significantly improved the stiffness and strength of Gr/Al composites。 Moreover， the results show that the existence of a graphene layer can effectively prevent the propagation of dislocations at the interface， thus improving the mechanical properties of the composites。 The deformation mechanism of the composites was studied by comparing the effects of the deformation behavior， compressive stress， and dislocation。 The dislocation movement of the Al matrix during compression was further investigated。 It was determined that stair-rod and Hirth dislocations occurred in the Al matrix， and the graphene layers exhibited bulging and kink deformation。 Furthermore， the mean curvature and Gaussian curvature of the compressed graphene surface were measured， and the deformation characteristics of graphene in the composites were considered using the geometric method。 We applied a new method to calculate the surface curvature and mechanical material deformation。
查看更多>>摘要：The shrinkage of sodium-poly(acrylate) PAA in divalent salt (strontium chloride (SrCl2) and barium chloride (BaCl2) solutions is investigated by atomistic molecular dynamics (MD) simulations to study the salt effect on PAA structure。 The salt concentration (Cs) was varied in the range of 0 < Cs < 1 M for fully charged PAA。 The PAA radius-of-gyration (Rg) decreases with Cs in the presence of both the divalent salts in qualitative agreement with experiments。 The PAA chain stiffness calculated in persistence length (Lp) decreases over the entire range of Cs。 At lower Cs， the PAA chains don't form aggregate， while at higher salt concentrations， PAA chains undergo self-association in both the divalent salts。 The PAA-Water H-bonds decreases with Cs significantly in the presence of BaCl2 as compared to SrCl2。 The PAA-Na+ radial distribution function (RDF) shows a decrease in its coordination number with Cs。 The distribution of salt-ions around PAA shows that the Ba2+ condensation onto PAA is more significant than Sr2+ because of a greater coordination number for the former than the latter。 Overall， the present study significantly advanced the molecular-level understanding of PAA microstructure in the dilute divalent metal salt solution。
查看更多>>摘要：Global structural searches performed for sodium amalgam compounds reveal six new and stable Na-Hg stoichiometries (e。g。， NaHg3， NaHg4， Na2Hg， Na4Hg， Na5Hg and Na6Hg) under ambient and high-pressure conditions。 With increasing Hg content in the compounds， the structure topology of Hg evolves from isolate atom (NamHgn， m/n >= 3， 0D)， linear chains (Na2Hg， 1D)， puckered honeycomb layers (Na3Hg2， 2D)， diamond networks (NaHg， 3D)， dodecahedron (NaHg2， 3D)， to tetrakaidecahedron (NaHg3， 3D)。 Electronic structure analysis shows that Hg can attain higher negative oxidation states， transferring more than one electron from Na atoms to the Hg 6p orbitals。 In NamHgn (m/n < 3) compounds， the covalent Hg-Hg interactions are found stemming from the sp hybridization。 In Na4Hg， quasi-zero-dimensional (0-D) electride is found with the electrons located within the octahedrons of Na in the lattice。 The present results establish the richness of sodium amalgam stoichiometries under ambient and high-pressure conditions。
查看更多>>摘要：Molecular dynamics simulations of graphene (G) or graphene oxide (GO) plates with epoxy， PDMS， or ABS were separately performed to investigate plate/polymer interactions。 The interactions were qualitatively assessed in larger models by visual observation of a G or GO plate's orientation with respect to polymer surfaces。 They were also quantitatively evaluated in smaller models for changes in potential and non-bonding energy during mixing。 The quantitative simulations allowed for the determination of energies of interaction that could not be detected in the larger qualitative studies， including aspects of plate alignment with respect to the polymer at the initiation of interactions。 Both the qualitative and quantitative simulations independently demonstrated polymer matrix plate composites (PMPCs) doped with GO resulted in greater stabilizing interactions than those doped with G。 In epoxy and ABS， GO showed 40-50% stronger interactions than G， while in PDMS， G had a strong de-stabilizing effect。
Ghumman, Umar Farooqvan Beek, AntonMunshi, JoydeepChien, TeYu...
11页
查看更多>>摘要：Molecular dynamics simulations have shown substantial promise in the design of organic photovoltaic cells (OPVC)。 Despite their potential， the utility of molecular dynamics simulations when designing an OPVC is often limited due to their considerable computational cost and their limited prediction accuracy。 To address these challenges， we introduce a three-step multi-fidelity design framework that enables a designer to efficiently explore the space of admissible processing conditions， using coarse-grained molecular dynamics (CGMD) sim-ulations， to identify the optimal OPVC design。 Using a novel spectral density based approach to reconstruct microstructures of variable size， the framework is able to sequentially search for the globally optimal micro-structure using a low-fidelity CGMD simulation with a smaller window size， followed by the optimization of the processing conditions using the high-fidelity simulation。 The division in two steps and two fidelities enables the optimization of CGMD simulations at previously intractable lengths and timescales。 We validate our results by demonstrating that the CGMD model predictions are consistent with physical experiments reported in the literature and corroborate that the computational complexity is reduced by one order of magnitude。
查看更多>>摘要：We present mechanoChemML， a machine learning software library for computational materials physics。 mechanoChemML is designed to function as an interface between platforms that are widely used for machine learning on one hand， and others for solution of partial differential equations-based models of physics。 Of special interest here， and the focus of mechanoChemML， are applications to computational materials physics。 These typically feature the coupled solution of material transport， reaction， phase transformation， mechanics， heat transport and electrochemistry。 Central to the organization of mechanoChemML are machine learning workflows that arise in the context of data-driven computational materials physics。 The mechanoChemML code structure is described， the machine learning workflows are laid out and their application to the solution of several problems in materials physics is outlined。
NSTL
Elsevier