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Computational Materials Science
Elsevier Science Publishers B.V.
Computational Materials Science

Elsevier Science Publishers B.V.

0927-0256

Computational Materials Science/Journal Computational Materials ScienceISTPSCIEI
正式出版
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    Lattice inversion potential with neural network corrections for metallic systems

    Wu, FeifengDuan, XianbaoQian, PingMin, Hang...
    11页
    查看更多>>摘要：By combining the lattice inversion method and the back-propagation neural network (BPNN), we have developed a neural network-based lattice inversion potential (NN-LIP). The lattice inversion method is used to describe the pairwise interaction, and the BPNN is used to describe the many-body correction term. NN-LIP has been applied successfully to six representative noble metal systems, including Au, Ag, Pd, Pt, Ir, and Rh. The results show that NN-LIP can reproduce the results calculated by first-principles accurately, including binding energy, lattice constant, elastic constant and a series of energy curves of different lattice structured metals, greatly expanding the applicability of lattice inversion potentials. Furthermore, compared to pure machine learning potential, NN LIP exhibits better robustness and generalization in regions not covered by the dataset used for training, which is due to the use of pairwise potential as the skeleton. NN-LIP provides a new theoretical framework for constructing high-precision potentials.
      原文链接:
    • NSTL
    • Elsevier

    TeaNet: Universal neural network interatomic potential inspired by iterative electronic relaxations

    Takamoto, SoIzumi, SatoshiLi, Ju
    24页
    查看更多>>摘要：A universal interatomic potential for an arbitrary set of chemical elements is urgently needed in computational materials science. Graph convolution neural network (GCN) has rich expressive power, but previously was mainly employed to transport scalars and vectors, not rank >= 2 tensors. As classic interatomic potentials were inspired by tight-binding electronic relaxation framework, we want to represent this iterative propagation of rank >= 2 tensor information by GCN. Here we propose an architecture called the tensor embedded atom network (TeaNet) where angular interaction is translated into graph convolution through the incorporation of Euclidean tensors, vectors and scalars. By applying the residual network (ResNet) architecture and training with recurrent GCN weights initialization, a much deeper (16 layers) GCN was constructed, whose flow is similar to an iterative electronic relaxation. Our training dataset is generated by density functional theory calculation of mostly chemically and structurally randomized configurations. We demonstrate that arbitrary structures and reactions involving the first 18 elements on the periodic table (H to Ar) can be realized satisfactorily by TeaNet, including C-H molecular structures, metals, amorphous SiO2, and water, showing surprisingly good performance (energy mean absolute error 19 meV/atom) and robustness for arbitrary chemistries involving elements from H to Ar.
      原文链接:
    • NSTL
    • Elsevier

    Transport behavior and thermoelectric properties of SnSe/SnS heterostructure modulated with asymmetric strain engineering

    Wu, MengnanAbbas, GhulamYang, WeifanLiu, Fusheng...
    9页
    查看更多>>摘要：Strain engineering of two-dimensional materials provides specific regulation method for the crystal structure, electric transport behavior and hence thermoelectric properties. Since the layer components of the van der Waals heterojunction exhibit discrepant response to strains, it provides a platform for manipulation of emergent electronic and thermoelectric properties. Here, motivated by the promising thermoelectric materials SnSe and its analogue, we design a specific high-promising thermoelectric candidate based on SnSe-SnS heterostructures, focusing on the strain induced asymmetric bonding-transition and its effect on thermoelectric properties. The compressed SnS/SnSe hetero-bilayer shows significantly enhanced anisotropic electrical transport properties, due to depressed carrier scattering rate along the robust weak bonding direction. In this armchair direction, extremely high power factor values (3600 mu W/(cm.K-2) for n-type and 4000 mu W/(cm.K-2) for p-type) are predicted at similar to 10(21) cm(-3) at 700 K. We obtain a new state-of-the-art thermoelectric material with extremely high thermoelectric power factor and pave the way for strain engineering of thermoelectric van der Waals heterostructures with robust in-plane weak bonding.
      原文链接:
    • NSTL
    • Elsevier

    Spinodal limits of supercooled liquid Al deduced from configuration heredity of crystal clusters

    Li, YuanLiu, ZhibangPeng, PingDong, Kejun...
    9页
    查看更多>>摘要：Whether one-component supercooled liquid encounters a spinodal limit at a sufficiently low temperature has been a controversial issue. To explore the homogeneous nucleation limit (HNL) in liquid Al, a series of molecular dynamics simulations have been performed, and a unique technique able to distinguish the critical nucleus from various embryos has been adopted to measure the crystal nucleation time tau(N) of supercooled liquids and evaluate the nucleation energy barrier Delta E-cri* in isothermal crystallization. The estimated kinetic spinodal (i.e., HNL) temperature T-ks and thermodynamic spinodal temperature T-ts are 0.51 Tm and 0.45 Tm, respectively. At the HNL, the nucleation energy barrier Delta E-cri* is discovered to be very small, and a critical slowdown behavior is also observed near T-ks. A careful analysis for the Stokes-Einstein (SE) relation reveals the temperature T-SE of SE relation breakdown is only 0.02 T-m higher than T-ks, and the occurrence of HNL is not affected by whether the SE relation breaks down or not. These results are consistent with previous reports. To some extent, the small gap between T-SE and T-ks can be attributed to a weak glass formation ability of liquid Al.
      原文链接:
    • NSTL
    • Elsevier

    Computational synthesis of 2D materials: A high-throughput approach to materials design

    Boland, Tara M.Singh, Arunima K.
    10页
    查看更多>>摘要：2D materials find promising applications in next-generation devices, however, large-scale, low-defect, and reproducible synthesis of 2D materials remains a challenging task. To assist in the selection of suitable substrates for the synthesis of as-yet hypothetical 2D materials, we have developed an open-source high throughput workflow package, Hetero2d, that searches for low-lattice mismatched substrate surfaces for any 2D material and determines the stability of these 2D-substrate heterostructures using density functional theory (DFT) simulations. Hetero2d automates the generation of 2D-substrate heterostructures, the creation of DFT input files, the submission and monitoring of computational jobs on supercomputing facilities, and the storage of relevant parameters alongside the post-processed results in a MongoDB database. We demonstrate the capability of & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp;Hetero2d in identifying stable 2D-substrate heterostructures for four 2D materials, namely 2H- MoS2, 1T- and 2H-NbO2, and hexagonal-ZnTe, considering 50 cubic elemental substrates. We find Cu, Hf, Mn, Nd, Ni, Pd, Re, Rh, Sc, Ta, Ti, V, W, Y, and Zr substrates sufficiently stabilize the formation energies of these 2D materials, with binding energies in the range of ~0.1-0.6 eV/atom. Upon examining the z-separation, the charge transfer, and the electronic density of states at the 2D-substrate interface, we find a covalent type bonding at the interface which suggests that these substrates can be used as contact materials for the 2D materials. Hetero2d is available on GitHub as an open-source package under the GNU license.
      原文链接:
    • NSTL
    • Elsevier

    The effect of network topology on material properties in vinyl-ester/styrene thermoset polymers using molecular dynamics simulations and time-temperature superposition

    Huang, MingAlvarez, Nicolas J. J.Palmese, Giuseppe R. R.Abrams, Cameron...
    9页
    查看更多>>摘要：The time-temperature superposition principle (TTSP) is a promising tool for filling the time-scale gap between molecular dynamics simulation and experiments in polymer systems. Here we propose a molecular dynamics approach to generate vinyl-ester (VE)/styrene (ST) thermoset modulus master curves that are comparable to experiments. Using this approach we generate modulus master curves for VE/ST systems which were generated with various relative reactivity ratios and therefore with vastly different network architectures. The master curves show that, while network architecture is irrelevant for glassy-state moduli measured either at low temperature or high frequencies, it can strongly determine rubbery-state behavior measured at high temperatures or low frequencies. The most important aspects of network architecture are the length of dangling chains and the molecular weight between crosslinks M-c, both of which depend on the relative reactivity of vinyl ester to styrene. We show that the modulus in the transition region between the glassy and rubbery states decreases with increasing M(c )at constant monomer composition. Our results provide an explanation for the observation that processing conditions that can affect relative reactivity, such as the processing temperature, can influence Mc and dictate material properties through specific topological features of the cured networks.
      原文链接:
    • NSTL
    • Elsevier

    Robustness of specimen design criteria for identification of anisotropic mechanical behaviour from heterogeneous mechanical fields

    Langrand, BertrandNotta-Cuvier, DelphineMarkiewicz, EricThoby, Jean-David...
    13页
    查看更多>>摘要：To reduce the number of tests required to characterize anisotropic elastoplastic constitutive models, an approach is to design specimen geometries to diversify the stress states generated in a single test. The experiments are then processed using an inverse identification method based on full-field measurements to achieve the full potential of that specific test. Recent optimization methods were able to design complex specimens in which highly heterogeneous stress fields were generated. However, the specimen design is only assessed based on numerical simulations and does not consider the effect of the biases introduced by the full -field measurement method. The goal of this work is therefore to take into account some of the most frequently observed measurement biases in the specimen selection process. The proposed approach uses synthetic test images generated with numerical simulations. Four specimen geometries have been ranked based on two selection criteria. The first one is an indicator of the heterogeneity of the stress fields obtained by finite element simulations (unbiased data). The second one quantifies error for the identification procedure due to measurement biases. The two criteria provide different rankings for the set of specimens. It is concluded that the design with the most heterogeneous stress fields (first criterion) is not necessarily the more robust design in terms of measurement noise (second criterion), so the optimized geometry should be selected based on a compromise between these two criteria.
      原文链接:
    • NSTL
    • Elsevier

    Determination of the structure of lithium niobosilicate glasses by molecular dynamics simulation with a new Nb-O potential

    Sun, WeiVeenhuizen, KeithMarsh, JacobDierolf, Volkmar...
    11页
    查看更多>>摘要：ABS T R A C T A partial charge empirical potential for the Nb-O pair has been developed based on existing parameters of other pairs in a Teter potential to enable molecular dynamics simulations of both lithium niobate crystal and lithium niobosilicate glasses. The developed potential is capable of describing structural features of lithium niobosilicate glasses in a wide composition range, including niobium coordination number and bond length, density, bond angle distribution, polyhedral distribution and fraction of bridging oxygen. The results obtained using this new potential show good agreement with experimental data of density and structure from Raman spectroscopy of lithium niobosilicate glasses and X-ray absorption spectroscopy near Nb K-edge.
      原文链接:
    • NSTL
    • Elsevier

    Unusual structure and properties of germanium under pressure

    Li, PeifangLang, HongyunBao, XinFeng, Chunsheng...
    7页
    查看更多>>摘要：Structural phase transitions in group 14 element germanium (Ge) under high pressure were investigated through first-principle calculations along with unbiased CALYPSO structure prediction method. We successfully reproduced experimental structures Fd-3m, I4(1)/amd, Imma, P6/mmm, Cmca and P6(3)/mmc were in our study on crystal structures. In addition, we found four new high-pressure metastable phases (Fmmm(I) and Cmcm at 75 GPa, Fmmm(II) and Fmm2 at 130 GPa). It was found in electronic density of states (DOS) and electronic band structure diagrams that all predicted new phases were metallic phases. The results of crystal structures, X-ray diffraction and phonon dispersion curve showed that our predicted phases (Cmcm and Fmmm(II)) could be incommensurate modulation structures. The findings of this study enriched the phases of Ge under high pressures and offered fundamental insight for further investigation of structural phase transitions in other group 14 elements under high pressures.
      原文链接:
    • NSTL
    • Elsevier

    Mechanism of complete dehydrogenation of ammonia borane in electrochemical alkaline environment

    Zhang, QuanHe, ChaozhengHuo, Jinrong
    9页
    查看更多>>摘要：Ammonia borane (NH3BH3, AB) has been considered to be a promising chemical hydrogen storage material. The dehydrogenation reaction of AB on the surface of MgSiP2 is investigated by the first-principles method. We have verified the two conventional intramolecular dehydrogenation pathways in the AB hydrolysis reaction, B-distal dehydrogenation (the rate-determining step (RDS) was 0.71 eV) and B-N bond dissociation dehydrogenation (the RDS was 1.00 eV). A new reaction route for dehydrogenation, the BN alternate dehydrogenation, was also explored. The reaction heat of the RDS was 0.71 eV. Note that the entire reaction process in the path of the dissociation of the BN bond can completely release the 6H protons in AB. With the help of the dissociation of H2O, the H-2 output ratio of 1:6 can be achieved. In addition, we also considered the influence of *OH- on the RDS of each dehydrogenation reaction in alkaline environment. The calculations have found that the presence of *OH- is beneficial to reduce the reaction heat of dehydrogenation in the AB hydrolysis reaction, making the reaction heat of the RDS of B-distal dehydrogenation is changed from 0.71 eV to 0.15 eV, the B-N bond dissociation dehydrogenation is changed from 1.00 eV to 0.09 eV and the BN alternate dehydrogenation is changed from 0.71 eV to 0.15 eV. This shows that *OH- greatly promotes the production of H-2 from the dehydrogenation of AB.
      原文链接:
    • NSTL
    • Elsevier