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End-to-end symmetry preserving inter-atomic potential energy model for finite and extended systems 32

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End-to-end symmetry preserving inter-atomic potential energy...

32nd Conference on Neural Information processing Systems, NeurIPS 2018

作者： Zhang, Linfeng Han, Jiequn Wang, Han Saidi, Wissam A. Car, Roberto Weinan, E. Program in Applied and Computational Mathematics Princeton University United States Institute of Applied Physics and Computational Mathematics China CAEP Software Center for High Performance Numerical Simulation China Department of Mechanical Engineering and Materials Science University of Pittsburgh United States Department of Chemistry Department of Physics Princeton University United States Princeton Institute for the Science and Technology of Materials Princeton University United States Department of Mathematics Princeton University United States Beijing Institute of Big Data Research China

Machine learning models are changing the paradigm of molecular modeling, which is a fundamental tool for material science, chemistry, and computational biology. Of particular interest is the inter-atomic potential energy surface (PES). Here we develop Deep Potential - Smooth Edition (DeepPot-SE), an end-to-end machine learning-based PES model, which is able to efficiently represent the PES of a wide variety of systems with the accuracy of ab initio quantum mechanics models. By construction, DeepPot-SE is extensive and continuously differentiable, scales linearly with system size, and preserves all the natural symmetries of the system. Further, we show that DeepPot-SE describes finite and extended systems including organic molecules, metals, semiconductors, and insulators with high fidelity. © 2018 Curran Associates Inc..All rights reserved.

关键词： Potential energy

Reflection-asymmetric wormholes and their double shadows

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Physical Review D 2020年第8期102卷 084044-084044页

作者： Maciek Wielgus Jiří Horák Frederic Vincent Marek Abramowicz Nicolaus Copernicus Astronomical Centre Polish Academy of Sciences Bartycka 18 00-716 Warsaw Poland Research Center for Computational Physics and Data Processing Institute of Physics Silesian University in Opava Bezručovo náměstí 1150/13746 01 Opava Czech Republic and Department of Physics Göteborg University 412-96 Göteborg Sweden

We discuss construction and observational properties of wormholes obtained by connecting two Reissner-Nordström spacetimes with distinct mass and charge parameters. These objects are spherically symmetric, but not reflection symmetric, as the connected spacetimes differ. The reflection-asymmetric wormholes may reflect a significant fraction of the infalling radiation back to the spacetime of its origin. We interpret this effect in a simple framework of the effective photon potential. Depending on the model parameters, image of such a wormhole seen by a distant observer (its “shadow”) may contain a photon ring formed on the observer’s side, photon ring formed on the other side of the wormhole, or both photon rings. These unique topological features would allow us to firmly distinguish this class of objects from Kerr black holes using radioastronomical observations.

关键词： Classical black holes General relativity General relativity equations & solutions Radio, microwave, & sub-mm astronomy

Emission-Line Diagnostics at z > 4: [O III]λ4363/Hγ

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arXiv 2025年

作者： Backhaus, Bren E. Cleri, Nikko J. Trump, Jonathan R. Kirkpatrick, Allison Simons, Raymond C. Haro, Pablo Arrabal Bagley, Micaela B. Brooks, Madisyn Calabrò, Antonello Davis, Kelcey Dickinson, Mark Finkelstein, Steven L. Hirschmann, Michaela Kartaltepe, Jeyhan S. Koekemoer, Anton M. Llerena, Mario Pacucci, Fabio Pirzkal, Nor Papovich, Casey Wilkins, Stephen M. Department of Physics and Astronomy University of Kansas LawrenceKS66045 United States Department of Physics University of Connecticut 196A Auditorium Road Unit 3046 StorrsCT06269 United States Department of Astronomy and Astrophysics The Pennsylvania State University University ParkPA16802 United States Institute for Computational and Data Sciences The Pennsylvania State University University ParkPA16802 United States Institute for Gravitation and the Cosmos The Pennsylvania State University University ParkPA16802 United States NSF’s National Optical-Infrared Astronomy Research Laboratory 950 N. Cherry Ave. TucsonAZ85719 United States Department of Astronomy The University of Texas at Austin AustinTX United States INAF Osservatorio Astronomico di Roma Via Frascati 33 Monteporzio Catone Rome00078 Italy Observatoire de Sauverny Versoix1290 Switzerland Laboratory for Multiwavelength Astrophysics School of Physics and Astronomy Rochester Institute of Technology 84 Lomb Memorial Drive RochesterNY14623 United States Space Telescope Science Institute 3700 San Martin Dr. BaltimoreMD21218 United States INAF - Osservatorio Astronomico di Roma via di Frascati 33 Monte Porzio Catone00078 Italy Center for Astrophysics | Harvard & Smithsonian 60 Garden St CambridgeMA02138 United States Black Hole Initiative Harvard University 20 Garden St CambridgeMA02138 United States ESA AURA Space Telescope Science Institute United States Department of Physics and Astronomy Texas A&M University College StationTX77843-4242 United States George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy Texas A&M University College StationTX77843-4242 United States Astronomy Centre University of Sussex Falmer BrightonBN1 9QH United Kingdom Institute of Space Sciences and Astronomy University of Malta MsidaMSD 2080 Malta

We use JWST Near-Infrared Spectrograph (NIRSpec) observations from the the Cosmic Evolution Early Release survey (CEERS), GLASS-JWST ERS (GLASS), and JWST Advanced Deep Extragalactic Survey (JADES) to measure rest-frame optical emission-line ratios of 90 galaxies at z > 4. The stacked spectra of galaxies with and without a broad-line feature reveal a difference in the [O III]λ 4363 and Hγ ratios. This motivated our investigation of the [O III]λ4363/Hγ vs [Ne III]/[O II] diagram. We define two AGN/SF classification lines based on 1869 SDSS galaxies at z ∼ 0. After applying a redshift correction to the AGN/SF lines we find 76.8% of BLAGN continue to land in the AGN region of the diagnostic largely due to the [Ne III]/[O II] ratio. However, 40.2% of non-BLAGN land in the AGN region as well, this could be due to star forming galaxies having harder ionization of there are narrow line AGN which are not accounted for. This indicates the potential of the [Ne III]/[O II]ratio to continue classifying galaxies to z ∼ 6. We further inspect galaxies without broad emission lines in each region of [O III]λ4363/Hγ vs [Ne III]/[O II] diagram and found that they have slightly stronger C III]λ1908 fluxes and equivalent width when landing in the BLAGN region. However, the cause of this higher ionization is unclear. Additionally, we find that BLAGN are characterized by a higher ionization (at constant electron temperature) compared to non-broad line galaxies. © 2025, CC BY.

关键词： Cosmology

Timescale of twin-peak quasi-periodic oscillations and mass of accreting neutron stars

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arXiv 2019年

作者： Török, Gabriel Goluchová, Kateřina Šrámková, Eva Urbanec, Martin Straub, Odele Institute of Physics and Research Centre for Computational Physics and Data Processing Silesian University in Opava Bezručovo nám. 13 OpavaCZ-74601 Czech Republic Max Planck Institute for extraterrestrial Physics Gießenbachstraße 1 Garching85748 Germany

Einstein’s general relativity predicts that orbital motion of accreted gas approaching a neutron star (NS) in a NS low-mass X-ray binary (LMXB) system occurs on a time scale proportional to the NS mass. Radiation of the gas accounts for most of the observed LMXBs variability. In more than a dozen of sources twin-peak quasi-periodic oscillations (QPOs) have been observed. Inspired by the expected proportionality between periods of orbital motion and NS mass we present a straightforward comparison among these sources. We investigate relations between QPO periods and their ratios and identify characteristic time scales of QPOs associated to individual sources. These timescales are likely determined by the relative mass of each NS. We show that the characteristic time scale of the millisecond pulsar XTE J1807.4-294 is longer than for most other NS LMXBs. Consequently, models of QPOs that consider geodesic orbital frequencies imply that the X-ray pulsars’ mass has to be about 50% higher than the average mass of other sources. Consideration of other X-ray pulsars indicates that the exceptionality of XTE J1807.4-294 cannot be related to NS magnetic field in any simple manner. We suggest that QPOs observed in this source can help to discriminate between the proposed versions of the NS equation of state. Copyright © 2019, The Authors. All rights reserved.

关键词： Time measurement

ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -XXI. A Large-sample Observational Study of Ethanol and Dimethyl Ether in Hot Cores

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arXiv 2025年

作者： Kou, Zhiping Li, Xiaohu Qin, Sheng-Li Liu, Tie Mannfors, E. Tang, Xindi Gorai, Prasanta Garay, Guido Das, Swagat R. García, Pablo Bronfman, Leonardo Juvela, M. Chen, Li Liu, Xunchuan Sanhueza, Patricio Peng, Yaping Chen, Long-Fei Zou, Jiahang Yang, Dongting Tóth, L. Viktor Dewangan, Lokesh Liu, Hong-Li Chibueze, James O. Li, Ziyang Xinjiang Astronomical Observatory Chinese Academy of Sciences 150 Science 1-Stree Urumqi Xinjiang830011 China University of Chinese Academy of Sciences Beijing100049 China School of Physics and Astronomy Yunnan University Kunming650091 China Xinjiang Key Laboratory of Radio Astrophysics 150 Science 1-Street Urumqi Xinjiang830011 China Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China Department of Physics University of Helsinki PO Box 64 Helsinki00014 Finland Rosseland Centre for Solar Physics University of Oslo PO Box 1029 Blindern Oslo0315 Norway Institute of Theoretical Astrophysics University of Oslo PO Box 1029 Blindern Oslo0315 Norway Departamento de Astronomía Universidad de Chile Las Condes Santiago7591245 Chile Chinese Academy of Sciences South America Center for Astronomy National Astronomical Observatories CAS Beijing100101 China Department of Earth and Planetary Sciences Institute of Science Tokyo Meguro Tokyo152-8551 Japan National Astronomical Observatory of Japan National Institutes of Natural Sciences 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Department of Astronomical Science SOKENDAI The Graduate University for Advanced Studies 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Department of Physics Faculty of Science Kunming University of Science and Technology Kunming650500 China School of Physics and Electronic Science Guizhou Normal University Guiyang550025 China Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing Guiyang550025 China Department of Astronomy Eötvös Loránd University Pázmány Péter sétány 1/A BudapestH-1117 Hungary University of Debrecen Faculty of Science and Technology Egyetemtér 1 DebrecenH-4032 Hungary Physical Research Laboratory Navrangpura Ahmedabad380 009 India Department of Mathematical Sciences University of South Africa Cnr Christian de Wet Rd and Pioneer Avenue Florida Park Roodepoort1709 South Africa Centre for Sp

Hot cores, as a stage of massive star formation, exhibit abundant line emissions of COMs. We present a deep line survey of two isomers of C2H6O: ethanol (C2H5OH;EA), and dimethyl ether (CH3OCH3;DE) as well as their possible precursor CH3OH towards 60 hot cores by using the ALMA 3 mm line observations. EA is detected in 40 hot cores and DE is detected in 59 hot cores. Of these, EA and DE are simultaneously detected in 39 hot cores. We calculate rotation temperatures and column densities of EA and DE by using the XCLASS software. The average rotation temperature of EA is higher than that of DE, whereas the average column density of EA is lower than that of DE. Combined with previous studies of hot cores and hot corinos, we find strong column density correlations among EA and DE (ρ = 0.92), EA and CH3OH (ρ = 0.82), as well as DE and CH3OH (ρ = 0.80). The column density ratios of EA/DE versus the column densities of CH3OH remain nearly constant with values within ~1 order of magnitude. These strong correlations and the stable ratios, suggest that EA, DE, and CH3OH could be chemically linked, with CH3OH potentially serving as a precursor for EA and DE. Compared with chemical models, the three different warm-up timescale models result in the systematic overproduction of EA and the systematic underproduction of DE. Therefore, our large sample observations can provide crucial constraints on chemical models. Copyright © 2025, The Authors. All rights reserved.

关键词： Giant stars

A Comparison of Approximate Analytic and Neural Network Solutions for Effective Mass Schrodinger Equation With Yukawa's Potential 2

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A Comparison of Approximate Analytic and Neural Network Solu...

2nd IEEE International Conference on Artificial Intelligence in Everything, AIE 2022

作者： Fotso Kamsu, Brigitte Vubangsi, Mercel Tchoffo, M. Al-Turjman, Fadi University of Dschang Condensed Matter Electronics and Signal Processing Research Unit Department of Physics Faculty of Science Cameroon Near East University Ai and Robotics Institute Artificial Intelligence Engineering Dept. Nicosia Turkey University of Bamenda Nwr Computational Materials Science Lab Department of Computer Science Htttc Bambili Cameroon University of Kyrenia Research Center for Ai and IoT Faculty of Engineering Kyrenia Cyprus

ISBN: (数字)9781665474009

ISBN: (纸本)9781665474009

We model a compositionally graded heterostructure using the effective mass approach with a screened Coulomb potential. Approximate analytical solutions to the model are compared with a Neural Network output and good agreement is achieved, paving the way for Artificial Intelligence modeling of systems with graded composition. © 2022 IEEE.

关键词： Grading

Machine learning interatomic potential for molecular dynamics simulation of the ferroelectric KNbO3 perovskite

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Physical Review B 2023年第1期107卷 014101-014101页

作者： Hao-Cheng Thong XiaoYang Wang Jian Han Linfeng Zhang Bei Li Ke Wang Ben Xu State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Beijing 100084 People's Republic of China Graduate School China Academy of Engineering Physics Beijing 100193 People's Republic of China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 People's Republic of China Beijing Institute of Big Data Research Beijing 100871 People's Republic of China School of Materials Science and Engineering Research Center for Materials Genome Engineering Wuhan University of Technology Wuhan 430070 People's Republic of China

Ferroelectric perovskites have been ubiquitously applied in piezoelectric devices for decades, among which ecofriendly lead-free (K,Na)NbO3−based materials have been recently demonstrated to be an excellent candidate for sustainable development. Molecular dynamics is a versatile theoretical calculation approach for the investigation of the dynamical properties of ferroelectric perovskites. However, molecular dynamics simulation of ferroelectric perovskites has been limited to simple systems, since the conventional construction of interatomic potential is rather difficult and inefficient. In the present study, we construct a machine-learning interatomic potential of KNbO3 [as a representative system of (K,Na)NbO3] by using a deep neural network model. Including first-principles calculation data into the training data set ensures the quantum-mechanics accuracy of the interatomic potential. The molecular dynamics based on machine-learning interatomic potential shows good agreement with the first-principles calculations, which can accurately predict multiple fundamental properties, e.g., atomic force, energy, elastic properties, and phonon dispersion. In addition, the interatomic potential exhibits satisfactory performance in the simulation of domain wall and temperature-dependent phase transition. The construction of interatomic potential based on machine learning could potentially be transferred to other ferroelectric perovskites and consequently benefit the theoretical study of ferroelectrics.

关键词： Domain walls Elasticity Ferroelectricity First-principles calculations Phase transitions Phonons Piezoelectricity Machine learning Molecular dynamics

Approximate relation between black hole perturbation theory and numerical relativity

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Physical Review D 2023年第12期108卷 124046-124046页

作者： Tousif Islam Gaurav Khanna Department of Physics University of Massachusetts Dartmouth Massachusetts 02747 USA Department of Mathematics University of Massachusetts Dartmouth Massachusetts 02747 USA Center for Scientific Computing and Data Science Research University of Massachusetts Dartmouth Massachusetts 02747 USA Department of Physics and Center for Computational Research University of Rhode Island Kingston Rhode Island 02881 USA

We investigate the interplay between numerical relativity (NR) and adiabatic point-particle black hole perturbation theory (ppBHPT) in the comparable mass regime for quasicircular nonspinning binary black holes. Specifically, we reassess the α−β scaling technique, previously introduced by Islam et al. [Surrogate model for gravitational wave signals from nonspinning, comparable-to large-mass-ratio black hole binaries built on black hole perturbation theory waveforms calibrated to numerical relativity, Phys. Rev. D 106, 104025 (2022)], as a means to effectively match ppBHPT waveforms to NR waveforms within this regime. In particular, α rescales the amplitude and β rescales the time (and hence the phase). Utilizing publicly available long NR data (SXS:BBH:2265 [SXS Collaboration, Binary black-hole simulation SXS:BBH:2265 (2019)]) for a mass ratio of 1∶3, encompassing the final ∼65 orbital cycles of the binary evolution, we examine the range of applicability of such scalings. We observe that the scaling technique remains effective even during the earlier stages of the inspiral. Additionally, we provide commentary on the temporal evolution of the α and β parameters and discuss whether they can be approximated as constant values. Consequently, we derive the α−β scaling as a function of orbital frequencies and demonstrate that it is equivalent to a frequency-dependent correction. We further provide a brief comparison between post-Newtonian (PN) waveforms and the rescaled ppBHPT waveform at a mass ratio of 1∶3 and comment on their regime of validity. Finally, we explore the possibility of using PN theory to obtain the α−β calibration parameters and still provide a rescaled ppBHPT waveform that matches NR.

关键词： Gravitational waves

Warm dense matter simulation via electron temperature dependent deep potential molecular dynamics

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arXiv 2019年

作者： Zhang, Yuzhi Gao, Chang Zhang, Linfeng Wang, Han Chen, Mohan Center for Applied Physics and Technology HEDPS College of Engineering Peking University Beijing100871 China Beijing Institute of Big Data Research Beijing100871 China Program in Applied and Computational Mathematics Princeton University PrincetonNJ United States Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Huayuan Road 6 Beijing100088 China

Simulating warm dense matter that undergoes a wide range of temperatures and densities is challenging. Predictive theoretical models, such as quantum-mechanics-based first-principles molecular dynamics (FPMD), require a huge amount of computational resources. Herein, we propose a deep learning based scheme, called electron temperature dependent deep potential molecular dynamics (TDDPMD), for efficiently simulating warm dense matter with the accuracy of FPMD. The TDDPMD simulation is several orders of magnitudes faster than FPMD, and, unlike FPMD, its efficiency is not affected by the electron temperature. We apply the TDDPMD scheme to beryllium (Be) in a wide range of temperatures (0.4 to 2500 eV) and densities (3.50 to 8.25 g/cm3). Our results demonstrate that the TDDPMD method not only accurately reproduces the structural properties of Be along the principal Hugoniot curve at the FPMD level, but also yields even more reliable diffusion coefficients than typical FPMD simulations due to its ability to simulate larger systems with longer time. Copyright © 2019, The Authors. All rights reserved.

关键词： Molecular dynamics