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DPA-2:a large atomic model as a multitask learner

npj Computational materials 2024年第1期10卷 185-199页

作者： Duo Zhang Xinzijian Liu Xiangyu Zhang Chengqian Zhang Chun Cai Hangrui Bi Yiming Du Xuejian Qin Anyang Peng Jiameng Huang Bowen Li Yifan Shan Jinzhe Zeng Yuzhi Zhang Siyuan Liu Yifan Li Junhan Chang Xinyan Wang Shuo Zhou Jianchuan Liu Xiaoshan Luo Zhenyu Wang Wanrun Jiang Jing Wu Yudi Yang Jiyuan Yang Manyi Yang Fu-Qiang Gong Linshuang Zhang Mengchao Shi Fu-Zhi Dai Darrin M.York Shi Liu Tong Zhu Zhicheng Zhong Jian Lv Jun Cheng Weile Jia Mohan Chen Guolin Ke Weinan E Linfeng Zhang Han Wang AI for Science Institute BeijingP.R.China DP Technology BeijingP.R.China Academy for Advanced Interdisciplinary Studies Peking UniversityBeijingP.R.China State Key Lab of Processors Institute of Computing TechnologyChinese Academy of SciencesBeijingP.R.China University of Chinese Academy of Sciences BeijingP.R.China HEDPS CAPTCollege of EngineeringPeking UniversityBeijingP.R.China Ningbo Institute of Materials Technology and Engineering Chinese Academy of SciencesNingboP.R.China CAS Key Laboratory of Magnetic Materials and Devices and Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology Chinese Academy of SciencesNingboP.R.China School of Electronics Engineering and Computer Science Peking UniversityBeijingP.R.China Shanghai Engineering Research Center of Molecular Therapeutics&New Drug Development School of Chemistry and Molecular EngineeringEast China Normal UniversityShanghaiP.R.China Laboratory for Biomolecular Simulation Research Institute for Quantitative Biomedicine and Department of Chemistry and Chemical BiologyRutgers UniversityPiscatawayNJUSA Department of Chemistry Princeton UniversityPrincetonNJUSA College of Chemistry and Molecular Engineering Peking UniversityBeijingP.R.China Yuanpei College Peking UniversityBeijingP.R.China School of Electrical Engineering and Electronic Information Xihua UniversityChengduP.R.China State Key Laboratory of Superhard Materials College of PhysicsJilin UniversityChangchunP.R.China Key Laboratory of Material Simulation Methods&Software of Ministry of Education College of PhysicsJilin UniversityChangchunP.R.China International Center of Future Science Jilin UniversityChangchunP.R.China Key Laboratory for Quantum Materialsof Zhejiang Province Department of PhysicsSchool of ScienceWestlake UniversityHangzhouP.R.China Atomistic Simulations Italian Institute of TechnologyGenovaItaly State Key Laboratory of Physical Chemistry of Solid Surface iChEMCollege of Chemistry and Chemical EngineeringXiame

The rapid advancements in artificial intelligence(AI)are catalyzing transformative changes in atomic modeling,simulation,and ***-driven potential energy models havedemonstrated the capability to conduct large-scale,long-duration simulations with the accuracy of ab initio electronic structure ***,the model generation process remains a bottleneck for large-scale *** propose a shift towards a model-centric ecosystem,wherein a large atomic model(LAM),pretrained across multiple disciplines,can be efficiently fine-tuned and distilled for various downstream tasks,thereby establishing a new framework for molecular *** this study,we introduce the DPA-2 architecture as a prototype for ***-trained on a diverse array of chemical and materials systemsusing a multi-task approach,DPA-2demonstrates superior generalization capabilities across multiple downstream tasks compared to the traditional single-task pre-training and fine-tuning *** approach sets the stage for the development and broad application of LAMs in molecular and materials simulation research.

关键词： DPA establishing thereby

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Room-temperature spin-orbit torque switching in a manganite-based heterostructure

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Physical Review B 2022年第14期105卷 144419-144419页

作者： Liang Liu Guowei Zhou Xinyu Shu Changjian Li Weinan Lin Lizhu Ren Chenghang Zhou Tieyang Zhao Rui Guo Qidong Xie Han Wang Jing Zhou Ping Yang Stephen J. Pennycook Xiaohong Xu Jingsheng Chen Department of Materials Science and Engineering National University of Singapore Singapore 117575 Singapore Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education School of Chemistry and Materials Science Shanxi Normal University Taiyuan 041004 China Department of Materials Science and Engineering Southern University of Science and Technology Shenzhen 518055 China Department of Physics Xiamen University Xiamen 361005 China Department of Electrical and Computer Engineering National University of Singapore Singapore 117575 Singapore Singapore Synchrotron Light Source (SSLS) National University of Singapore 5 Research Link Singapore 117603 Singapore Suzhou Research Institute National University of Singapore Suzhou 215123 China Chongqing Research Institute National University of Singapore Chongqing 401120 China Institute of Material Research and Engineering Agency for Science Technology and Research (A*STAR) Singapore 138634 Singapore

The oxide ferromagnet La0.67Sr0.33MnO3 (LSMO) possesses low saturation magnetization (Ms), a low magnetic damping constant (α), and high carrier spin polarization, which promise superior functionalities in spintronics devices. For applications, these devices are to be integrated into electronic circuits, which require the control of the magnetization of LSMO by electrical means. However, a reliable electrical switching method remains largely unexplored. Here, we study the current-induced spin-orbit torque (SOT) in an all-oxide SrIrO3/LSMO bilayer. We found the magnetization of a 15 nm LSMO can be switched by electrical current, as confirmed from both the electrical transport measurement and the magnetic optical measurement. By taking advantage of the strain-mediated magnetic anisotropy, the magnetic easy axis of LSMO was controlled to be either perpendicular or parallel to the charge current direction such that a type-y or a type-x SOT switching was achieved, respectively. The dampinglike SOT efficiency is characterized to be 0.15 at room temperature according to the harmonic Hall voltage analysis. We also studied the temperature dependences of the SOT effective field and current-induced switching. Our demonstration of the electrical switching of LSMO magnetization at room temperature may stimulate SOT studies in a wide variety of all-oxide systems.

关键词： Magnetic anisotropy Magnetization switching Spin torque Ferromagnets Transition metal oxides Magneto-optical Kerr effect Scanning transmission electron microscopy X-ray diffraction

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Hyperuniformity and wave localization in pinwheel scattering arrays

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Physical Review B 2021年第22期103卷 224202-224202页

作者： F. Sgrignuoli L. Dal Negro Department of Electrical and Computer Engineering Boston University 8 Saint Mary's Street Boston Massachusetts 02215 USA Division of Material Science and Engineering Boston University 15 Saint Mary's Street Brookline Massachusetts 02446 USA Department of Physics Boston University 590 Commonwealth Avenue Boston Massachusetts 02215 USA

We investigate the structural and spectral properties of deterministic aperiodic arrays designed from statistically isotropic pinwheel tiling. By studying the scaling of the cumulative integral of its structure factor in combination with a higher-order structural correlation analysis we conclude that pinwheel arrays belong to the weakly hyperuniformity class. Moreover, by solving the multiple scattering problem for electric point dipoles using the rigorous Green's matrix theory, we demonstrate a clear transition from diffusive transport to localization behavior. This is shown by studying the Thouless number as a function of the scattering strength and the spectral statistics of the scattering resonances. Surprisingly, despite the absence of sharp diffraction peaks, clear spectral gaps are discovered in the density of states of pinwheel arrays that manifest a distinctive long-range order. Furthermore, the level-spacing statistics at large optical density exhibits a sharp transition from level repulsion to the Poisson behavior, consistently with the onset of the wave localization regime. Our findings reveal the importance of hyperuniform aperiodic structures with statistically isotropic k space for the engineering of enhanced light-matter interactions and localization properties.

关键词： Light-matter interaction Localization Mesoscopics Metamaterials Photonics

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Recent advancements in microfluidic-based biosensors for detection of genes and proteins: Applications and techniques

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Biosensors and Bioelectronics: X 2024年 19卷

作者： Siavashy, Saeed Soltani, M. Rahimi, Shayan Hosseinali, Mehraveh Guilandokht, Zahra Raahemifar, Kaamran Department of Mechanical Engineering K. N. Toosi University of Technology Tehran Iran Department of Electrical and Computer and Engineering University of Waterloo Waterloo Canada University of Waterloo Waterloo Canada Centre for Sustainable Business International Business University Toronto Canada Mork Family Department of Chemical Engineering and Material Science University of Southern California Los Angeles United States School of Pharmacy٫ Faculty of Science University of Waterloo Waterloo Ontario Canada 200 University Avenue West WaterlooONN2L 3G1 Canada Department of Life Sciences and Biotechnology Shahid Beheshti University Tehran Iran Penn State UniversityStateCollege PA16801 United States School of Optometry and Vision Science Faculty of Science University of Waterloo 200 University Ave. W WaterlooONN2L 3G1 Canada Department of Chemical Engineering Faculty of Engineering University of Waterloo 200 University Ave. W WaterlooONN2L 3G1 Canada

This article has tried to provide an overview of the most sophisticated microfluidic biosensors for identifying nucleic acids and proteins at the site of treatment. Microfluidics, which also automates sample preparation and reduces processing time and reagent consumption, enables the analysis of small sample quantities. Microfluidics and biosensor technologies collaborate to provide diagnostics at the point of care with high throughput analysis, portability, and disposability. The high sensitivity and selectivity requirements, false response errors, and integration with other essential modules are some of the challenges posed by this merger. The broad categories of protein-based and DNA-based biosensor technology are covered in this review. Also, recent advancements in coupling the biosensors to microfluidics, the main challenges and potential solutions in deploying microfluidic biosensors for point-of-care diagnostics, and the most recent developments in these areas have been discussed. © 2024

关键词： Biosensors

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Infrared dielectric functions and Brillouin zone center phonons of α-Ga2O3 compared to α-Al2O3

arXiv

引用

arXiv 2021年

作者： Stokey, Megan Korlacki, Rafal Hilfiker, Matthew Knight, Sean Richter, Steffen Darakchieva, Vanya Jinno, Riena Cho, Yongjin Xing, Huili Grace Jena, Debdeep Oshima, Yuichi Khan, Kamruzzaman Ahmadi, Elaheh Schubert, Mathias Department of Electrical and Computer Engineering University of Nebraska-Lincoln LincolnNE68588 United States Linköping University Linköping58183 Sweden School of Electrical and Computer Engineering Cornell University IthacaNY14853 United States Department of Electronic Science and Engineering Kyoto University Kyoto615-8510 Japan Department of Material Science and Engineering Cornell University IthacaNY14853 United States Optical Single Crystals Group National Institute for Materials Science Ibaraki Tsukuba3050044 Japan Electrical Engineering and Computer Science Department University of Michigan Ann ArborMI48109 United States

We determine the anisotropic dielectric functions of rhombohedral α-Ga2O3 by far-infrared and infrared generalized spectroscopic ellipsometry and derive all transverse optical and longitudinal optical phonon mode frequencies and broadening parameters. We also determine the high frequency and static dielectric constants. We perform density functional theory computations and determine the phonon dispersion for all branches in the Brillouin zone, and we derive all phonon mode parameters at the Brillouin zone center including Raman-active, infrared-active, and silent modes. Excellent agreement is obtained between our experimental and computation results as well as among all previously reported partial information from experiment and theory. We also compute the same information for α-Al2O3, the binary parent compound for the emerging alloy of α(AlxGa1−x)2O3, and use results from previous investigations [Schubert, Tiwald, and Herzinger, Phys. Rev. B 61, 8187 (2000)] to compare all properties among the two isostructural compounds. From both experimental and theoretical investigations we compute the frequency shifts of all modes between the two compounds. Additionally, we calculate overlap parameters between phonon mode eigenvectors and discuss the possible evolution of all phonon modes into the ternary alloy system and whether modes may form single mode or more complex mode behaviors. © 2021, CC BY.

关键词： Spectroscopic ellipsometry

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Heating of Cs2Te Photocathode via Field Emission and RF Pulsed Heating: Implication Toward Breakdown

arXiv

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arXiv 2025年

作者： Shinohara, Ryo Bagchi, Soumendu Simakov, Evgenya Perez, Danny Baryshev, Sergey V. Department of Electrical and Computer Engineering Michigan State University MI48824 United States Department of Physics and Astronomy Michigan State University East LansingMI48824 United States Theoretical Division Los Alamos National Laboratory Los AlamosNM87545 United States Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak RidgeTN37831 United States Accelerator Operations and Technology Division Los Alamos National Laboratory Los AlamosNM87545 United States Department of Chemical Engineering and Material Science Michigan State University MI48824 United States

The occurrence of radio-frequency (rf) breakdown limits operational electromagnetic gradients in accelerator structures. Experimental evidence often suggests that breakdown events are associated with temperature and dark current spikes on the surface of radiofrequency (RF) devices. In the past decade, there has been increased interest in unveiling the mechanism behind breakdown initiation in metal copper and copper alloys;however, effort regarding breakdown phenomenon in photocathode-relevant semiconductors have been more limited. In this work, we explore field-emission-assisted heating via Nottingham and Joule processes, as a possible candidate for breakdown initiation. For this, field emission from intrinsic Cs2Te ultra-thin film coated on a copper substrate was modeled within the Stratton–Baskin–Lvov–Fursey formalism, describing the processes and effects in the bulk and on the surface of a photocathode exposed to high radio-frequency electromagnetic fields. It is shown that field emission characteristic deviates significantly from the classical Fowler-Nordheim (FN) theory, whereby predicting that dark current is orders of magnitude lower than one expected by FN law. Conventional pulsed heating was also found to impose negligible heating to the photocathode. Both conclusions suggest that Cs2Te photocathode coated on a metal substrate would be insensitive to catastrophic thermal-material runaway breakdown, unlike what is observed for metal surfaces. Finally, a few unconventional breakdown candidate scenarios are identified and discussed including thermo-elastic deformation and avalanche breakdown. © 2025, CC BY.

关键词： Photocathodes

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Wave localization in number-theoretic landscapes

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Physical Review B 2022年第22期106卷 224203-224203页

作者： L. Dal Negro Y. Zhu Y. Chen M. Prado F. A. Pinheiro Department of Electrical and Computer Engineering & Photonics Center Boston University 8 Saint Mary's Street Boston Massachusetts 02215 USA Department of Physics Boston University 590 Commonwealth Avenue Boston Massachusetts 02215 USA Division of Material Science and Engineering Boston University 15 Saint Mary's Street Brookline Massachusetts 02446 USA Instituto de Física Universidade Federal do Rio de Janeiro Rio de Janeiro-RJ 21941-972 Brazil

We investigate the localization of waves in aperiodic structures that manifest the characteristic multiscale complexity of arithmetic functions with a central role in number theory. In particular, we study the eigenspectra and wave localization properties of tight-binding Schrödinger equation models with onsite potentials distributed according to the Liouville function λ(n), the Möbius function μ(n), and the Legendre sequence of quadratic residues modulo a prime. We employ multifractal detrended fluctuation analysis and establish the multifractal scaling properties of the energy spectra in these systems. Moreover, by systematically analyzing the spatial eigenmodes and their level spacing distributions, we show the absence of level repulsion with broadband localization across the entire energy spectra. Our study introduces finite-size aperiodic systems whose eigenmodes are all strongly localized and provide opportunities for unique quantum and classical devices of particular importance to cold-atom experiments with engineered speckle potentials as well as unique optical metamaterials and nanostructures with enhanced light-matter interactions.

关键词： Anderson localization Metamaterials Optics & lasers Schroedinger equation Tight-binding model

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Thermal and electric field driven breakdown precursor formation on metal surfaces

arXiv

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arXiv 2023年

作者： Shinohara, Ryo Bagchi, Soumendu Simakov, Evgenya Baryshev, Sergey V. Perez, Danny Department of Electrical and Computer Engineering Michigan State University MI48824 United States Department of Physics and Astronomy Michigan State University East LansingMI48824 United States Theoretical Division Los Alamos National Laboratory Los AlamosNM87545 United States Accelerator Operations and Technology Division Los Alamos National Laboratory Los AlamosNM87545 United States Department of Chemical Engineering and Material Science Michigan State University MI48824 United States

The phenomenon of electric breakdown poses serious challenge to the design of devices that operate under high gradient environments. Experimental evidence often points towards breakdown events that are accompanied by elevated temperatures and dark current spikes, presumably due to high-asperity nano-structure formation that enhances the local electric field and triggers a runaway process. However, the exact mechanistic origin of such nano-structures under typical macroscopic operational conditions of electric gradient and magnetic-field-mediated heating remains poorly understood. In this work, a model is presented that describes the evolution of a typical copper surface under the combined action of the electric fields and elevated temperatures. Using a mesoscale curvature-driven growth model, we show how the copper surface can undergo a type of dynamical instability that naturally leads to the formation of sharp asperities in realistic experimental conditions. Exploring the combined effect of fields and temperature rise, we identify critical regimes that allow for the formation of breakdown precursors. These regimes strongly resonate with previous experimental findings on breakdown of copper electrodes, hence suggesting surface diffusion to be a crucial breakdown precursor mechanism. © 2023, CC BY.

关键词： Copper

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Multi-fidelity Bayesian Optimization with Max-value Entropy Search and its Parallelization 37

Multi-fidelity Bayesian Optimization with Max-value Entropy ...

引用

37th International Conference on Machine Learning, ICML 2020

作者： Takeno, Shion Fukuoka, Hitoshi Tsukada, Yuhki Koyama, Toshiyuki Shiga, Motoki Takeuchi, Ichiro Karasuyama, Masayuki Department of Computer Science Nagoya Institute of Technology Aichi Japan Center for Advanced Intelligence Project Riken Tokyo Japan Department of Materials Design Innovation Engineering Nagoya University Aichi Japan PRESTO Japan Science and Technology Agency Saitama Japan Department of Electrical Electronic and Computer Engineering Gifu University Gifu Japan Center for Materials Research by Information Integration National Institute for Material Science Ibaraki Japan

ISBN: (纸本)9781713821120

In a standard setting of Bayesian optimization (BO), the objective function evaluation is assumed to be highly expensive. Multifidelity Bayesian optimization (MFBO) accelerates BO by incorporating lower fidelity observations available with a lower sampling cost. We propose a novel information-theoretic approach to MFBO, called multi-fidelity max-value entropy search (MF-MES), that enables us to obtain a more reliable evaluation of the information gain compared with existing information-based methods for MFBO. Further, we also propose a parallelization of MF-MES mainly for the asynchronous setting because queries typically occur asynchronously in MFBO due to a variety of sampling costs. We show that most of computations in our acquisition functions can be derived analytically, except for at most only two dimensional numerical integration that can be performed efficiently by simple approximations. We demonstrate effectiveness of our approach by using benchmark datasets and a real-world application to materials science data. © 2020 37th International Conference on Machine Learning, ICML 2020. All rights reserved.

关键词： Entropy

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Learning Optimal Strategies for Temporal Tasks in Stochastic Games

arXiv

引用

arXiv 2021年

作者： Bozkurt, Alper Kamil Wang, Yu Zavlanos, Michael M. Pajic, Miroslav Department of Computer Science Duke University DurhamNC27708 United States Department of Mechanical and Aerospace Engineering University of Florida GainesvilleFL32611 United States Department of Mechanical Engineering and Material Science Duke University DurhamNC27708 United States Department of Electrical and Computer Engineering Duke University DurhamNC27708 United States

Synthesis from linear temporal logic (LTL) specifications provides assured controllers for systems operating in stochastic and potentially adversarial environments. Automatic synthesis tools, however, require a model of the environment to construct controllers. In this work, we introduce a model-free reinforcement learning (RL) approach to derive controllers from given LTL specifications even when the environment is completely unknown. We model the problem as a stochastic game (SG) between the controller and the adversarial environment;we then learn optimal control strategies that maximize the probability of satisfying the LTL specifications against the worst-case environment behavior. We first construct a product game using the deterministic parity automaton (DPA) translated from the given LTL specification. By deriving distinct rewards and discount factors from the acceptance condition of the DPA, we reduce the maximization of the worst-case probability of satisfying the LTL specification into the maximization of a discounted reward objective in the product game;this enables the use of model-free RL algorithms to learn an optimal controller strategy. To deal with the common scalability problems when the number of sets defining the acceptance condition of the DPA (usually referred as colors), is large, we propose a lazy color generation method where distinct rewards and discount factors are utilized only when needed, and an approximate method where the controller eventually focuses on only one color. In several case studies, we show that our approach is scalable to a wide range of LTL formulas, significantly outperforming existing methods for learning controllers from LTL specifications in SGs. Copyright © 2021, The Authors. All rights reserved.

关键词： Controllers

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