Modeling the High-Pressure Solid and Liquid Phases of Tin from Deep Potentials with ab initio Accuracy

Constructing an accurate atomistic model for the high-pressure phases of tin (Sn) is challenging because properties of Sn are sensitive to pressures. We develop machine-learning-based deep potentials for Sn with pressures ranging from 0 to 50 GPa and temperatures ranging from 0 to 2000 K. In particular, we find the deep potential, which is obtained by training the ab initio data from density functional theory calculations with the state-of-the-art SCAN exchange-correlation functional, is suitable to characterize high-pressure phases of Sn. We systematically validate several structural and elastic properties of the {\alpha} (diamond structure), {\beta}, bct, and bcc structures of Sn, as well as the structural and dynamic properties of liquid Sn. The thermodynamics integration method is further utilized to compute the free energies of the {\alpha}, {\beta}, bct, and liquid phases, from which the deep potential successfully predicts the phase diagram of Sn including the existence of the triple-point that qualitatively agrees with the experiment

DeePMD-kit v2: A software package for Deep Potential models

DeePMD-kit is a powerful open-source software package that facilitates molecular dynamics simulations using machine learning potentials (MLP) known as Deep Potential (DP) models. This package, which was released in 2017, has been widely used in the fields of physics, chemistry, biology, and material science for studying atomistic systems. The current version of DeePMD-kit offers numerous advanced features such as DeepPot-SE, attention-based and hybrid descriptors, the ability to fit tensile properties, type embedding, model deviation, Deep Potential - Range Correction (DPRc), Deep Potential Long Range (DPLR), GPU support for customized operators, model compression, non-von Neumann molecular dynamics (NVNMD), and improved usability, including documentation, compiled binary packages, graphical user interfaces (GUI), and application programming interfaces (API). This article presents an overview of the current major version of the DeePMD-kit package, highlighting its features and technical details. Additionally, the article benchmarks the accuracy and efficiency of different models and discusses ongoing developments.Comment: 51 pages, 2 figure

Cellular Automata Modeling of Ostwald Ripening and Rayleigh Instability

A cellular automata (CA) approach to modeling both Ostwald ripening and Rayleigh instability was developed. Curvature-driven phase interface migration was implemented to CA model, and novel CA rules were introduced to ensure the conservation of phase volume fraction of nearly equilibrium two-phase system. For transient Ostwald ripening, it is shown that the temporal growth exponent m is evolving with time and non-integer temporal exponents between 2 and 3 are predicted. The varying temporal growth exponent m is related to the particle size distributions (PSDs) evolution. With an initial wide PSD, it becomes narrowed toward steady state. With an initial narrow PSD, it becomes widened at first and then narrowed toward steady state. For Rayleigh instability, two cases (one with sinusoidal perturbation on the surface of the long cylinder, and the other with grain boundaries in the interior of the long cylinder) were simulated, and the breakup of the long cylinder was shown for both cases. In the end, a system containing long cylinders with interior grain boundaries was simulated, which demonstrated the integration of Rayleigh instability and Ostwald ripening relating to the spheroidization of the lamellar structure

Effects of subgrain size and static recrystallization on the mechanical performance of polycrystalline material: A microstructure-based crystal plasticity finite element analysis

In this paper, the effects of subgrain size and static recrystallization on the mechanical performance of polycrystalline material were investigated using a microstructure-based crystal plasticity finite element (CPFE) model. Firstly, polycrystalline microstructures with different mean subgrain sizes were prepared using simple assumption based on experimental observations, and intermediate microstructures during static recrystallization (SRX) were simulated by a cellular automata model adopting curvature driven grain/subgrain growth mechanism. Then, CPFE method was applied to perform stress analysis of plane strain tension on these virtual microstructures. The results show that the subgrains inside pre-existing grains have an effect on the heterogeneity of the stress distributions. The average stress decreases with increasing the mean subgrain radius. As grain/subgrain grows during SRX, the average stress also decreases. It can be deduced that well-defined and finer subgrain structure may strengthen the polycrystalline material, while grain/subgrain growth during SRX process will degrade the strength

Experimental and Theoretical Study on Crown Ether-Appended-Fe(III) Porphyrin Complexes and Catalytic Oxidation Cyclohexene with O₂

Modifying non-precious metal porphyrins at the meso-position is sufficient to further improve the ability to activate O2 and the selectivity of the corresponding redox products. In this study, a crown ether-appended Fe(III) porphyrin complex (FeTC4PCl) was formed by replacing Fe(III) porphyrin (FeTPPCl) at the meso-position. The reactions of FeTPPCl and FeTC4PCl catalysed by O2 oxidation of cyclohexene under different conditions were studied, and three main products, 2-cyclohexen-1-ol (1), 2-cyclohexen-1-one (2), and 7-oxabicyclo[4.1.0]heptane (3), were obtained. The effects of reaction temperature, reaction time, and the addition of axial coordination compounds on the reactions were investigated. The conversion of cyclohexene reached 94% at 70 °C after 12 h, and the selectivity toward product 1 was 73%. The geometrical structure optimization, molecular orbital energy level analysis, atomic charge, spin density, and density of orbital states analysis of FeTPPCl, FeTC4PCl, as well as the oxygenated complexes (Fe-O2)TCPPCl and (Fe-O2)TC4PCl formed after adsorption of O2, were carried out using the DFT method. The results of thermodynamic quantity variation with reaction temperature and Gibbs free energy variation were also analysed. Finally, based on experimental and theoretical analysis, the mechanism of the cyclohexene oxidation reaction with FeTC4PCl as a catalyst and O2 as an oxidant was deduced, and the reaction mechanism was obtained as a free radical chain reaction process

Influence Mechanism of Cu Layer Thickness on Photoelectric Properties of IWO/Cu/IWO Films

Transparent conductive IWO/Cu/IWO (W-doped In2O3) films were deposited on quartz substrates by magnetron sputtering of IWO and Cu in the Ar atmosphere. The X-ray diffraction (XRD) patterns identified the cubic iron–manganese ore crystal structure of the IWO layers. The influence of the thickness of the intermediate ultra-thin Cu layers on the optical and electrical properties of the multilayer films was analyzed. As the Cu layer thickness increases from 4 to 10 nm, the multilayer resistivity gradually decreases to 4.5 × 10−4 Ω·cm, and the optical transmittance in the mid-infrared range increases first and then decreases with a maximum of 72%, which serves as an excellent candidate for the mid-infrared transparent electrode

Proteomic Insights into citT-Deletion Induced Metabolic Sensitivity in Bio-Degumming of Ramie Fibers by Bacillus subtilis

ABSTRACTCellulose fibers from ramie is a kind of functional biological material with multipurpose in the textile industry, which called as “China grass.” The degumming of ramie fibers performed with Bacillus subtilis were regulated by response regulator CitT from CitS/CitT two-component system through specifically functioning on the degradation of component pectin. In this study, comparative proteomic analysis was executed to obtain insights into the sensitivity by which the metabolic network induced by the absence of CitT protein, and to further explore the regulatory mechanism during bio-degumming process of ramie fibers. Results showed that 29 differentially expressed proteins were detected from original strain and mutant strain, which were mainly involved in transmembrane transport system, two-component system, and amino acid metabolism. This study demonstrated that the lack of CitT protein could result in the down-regulation of enzymes in histidine biosynthesis pathway, and the up-regulation of enzyme in arginine degradation pathway. This study is the first time to reveal comprehensive information about the regulatory function of CitT protein in bio-degumming of ramie fibers, and may provide important scientific and technological basis for targeted constructing engineering strains in degumming of ramie fibers

Chinese consumer preferences for organic labels on Oolong tea: evidence from a choice experiment

Repeated food scandals in China have prompted growing consumer consciousness on food safety and health. Organic food, considered to be of higher quality, is being increasingly demanded by Chinese consumers. This study examines preferences for organic labels to provide insight on the sustainable development of the Oolong tea industry. Research was conducted using the choice experiment (CE) method in Fujian and Guangdong Provinces. The results demonstrate that place of origin, organic label, and brand attributes are all significant factors affecting the purchase of Oolong. Also, people demonstrated significantly positive attitudes toward organic labels and preferred Oolong tea from Fujian Province to those from Guangdong Province and Taiwan. Increasing trust can enhance consumer preference and willingness to pay (WTP) for organic labels. Contrary to previous studies, people have a higher WTP for Chinese organic labels than Japanese and American ones. This is probably because respondents are more familiar with domestic Oolong tea and trust more in Chinese organic certification. This provides an opportunity for domestic producers to tailor their organic food labels and better satisfy consumer demands. These findings suggest that the Chinese government should take more responsibility for reducing food-related fraud and thus improve consumer trust regarding organic food

Solving Material Mechanics and Multiphysics Problems of Metals with Complex Microstructures Using DAMASK-The Dusseldorf Advanced Material Simulation Kit

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