检索结果-内蒙古大学图书馆

Single and double charge transfer in the Ne2++He collision within time-dependent density-functional theory

学校读者我要写书评

暂无评论

Physical Review A 2021年第3期103卷 032816-032816页

作者： Wandong Yu Cong-Zhang Gao Shunsuke A. Sato Alberto Castro Angel Rubio Baoren Wei Institute of Modern Physics Department of Nuclear Science and Technology Fudan University Shanghai 200433 China Key Laboratory of Nuclear Physics and Ion-beam Application (MOE) Fudan University Shanghai 200433 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China Center for Computational Sciences University of Tsukuba 1-1-1 Tennodai Tsukuba Ibaraki Japan Max Planck Institute for the Structure and Dynamics of Matter Luruper Chaussee 149 22761 Hamburg Germany ARAID Foundation 50018 Zaragoza Spain Institute for Biocomputation and Physics of Complex Systems University of Zaragoza Calle Mariano Esquillor 50018 Zaragoza Spain

We calculate the charge-transfer cross sections for the Ne2++He collision. To this end, we employ Ehrenfest molecular dynamics with time-dependent density-functional theory. The active electrons of the projectile are handled by applying an initial velocity to the Kohn-Sham orbitals via a Galilean boost. The dynamical calculations are performed in an inverse collision framework—the reference frame considers Ne2+ to be initially at rest, which ensures numerically converged final-time scattering states. The charge-transfer probabilities are extracted by extending the particle number projection technique to be able to handle the degenerate Ne2+ ion. Compared with experimental data available at 10–3000 keV, a fairly good agreement is found for the calculated single- and double-charge transfer cross sections, superior to other theoretical calculations for this Ne2++He collision. A time-resolved analysis of the charge-transfer probabilities finds that ionization to the continuum also takes place after the charge transfer has occurred. To account for it, the final scattering states should be followed for a long time, approximately 350 fs, until they stabilize.

关键词： Atomic & molecular collisions Charge-transfer collisions

Effects of Branching and Polydispersity on Thermal Conductivity of Paraffin Waxes

学校读者我要写书评

暂无评论

SSRN

SSRN 2022年

作者： Boomstra, M.W. van Asseldonk, M.W.J. Geurts, B.J. Nazarychev, V.M. Lyulin, A.V. Soft Matter and Biological Physics Department of Applied Physics Eindhoven University of Technology P.O. Box 513 Eindhoven5600 MB Netherlands Center for Computational Energy Research P.O. Box 6336 Eindhoven5600 HH Netherlands Multiscale Modeling and Simulation Department of Applied Mathematics Faculty EEMCS University of Twente P.O. Box 217 Enschede 7500AE Netherlands Institute of Macromolecular Compounds Russian Academy of Sciences Bolshoi Prospect V.O. 31 St. Petersburg199004 Russia

Paraffin waxes are promising phase change materials, abundantly available at very low cost. Having large latent heat, these materials can be used for thermal energy storage. However, when used in heat batteries, paraffin’s low thermal conductivity prevents fast charging and discharging. This calls for the design of tailored hybrid materials with improved properties, the present study concentrates on properties of pure paraffin wax. Using fully atomistic molecular-dynamics (MD) simulations, we study the effects of polydispersity and branching on the thermal conductivity of paraffin waxes, in molten (450 K) and solid (250 K) state. Both branching and polydispersity affect the density and especially the crystallinity of the solid. Branching has a pronounced effect on crystallisation caused by inhibited alignment of the polymer backbones while the effect of polydispersity is less pronounced. The thermal conductivity (TC) has been simulated using the reverse non-equilibrium molecular-dynamics method, as well as the equilibrium Green-Kubo approach. Increased branching, added to backbones comprised of twenty monomers, results in decreasing TC of up to 30%, polydispersity only has an effect in the semi-crystalline state. Comparison to available experiments shows good agreement which validates the model details, applied force field and the calculation *** show that at comparable computational costs, the reverse non-equilibrium MD approach produces more reliable results for TC, as compared to the equilibrium Green-Kubo method. The major contribution to TC by acoustic phonon transport along the backbone was shown by analysing extreme cases. The phonon density of states (PDOS) of samples with high branching or with small chain length displayed diminished peaks in the acoustic range as compared to the PDOS of samples with low branching or larger chain length, respectively. The suggested MD approach can definitely be used to investigate specific material modifications aime

关键词： Phase change materials

Manifestations of metastable criticality in the long-range structure of model water glasses

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Gartner, Thomas E. Torquato, Salvatore Car, Roberto Debenedetti, Pablo G. Department of Chemistry Princeton University PrincetonNJ United States Department of Physics Princeton University PrincetonNJ United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ United States Princeton Institute for the Science and Technology of Materials Princeton University PrincetonNJ United States Department of Chemical and Biological Engineering Princeton University PrincetonNJ United States

Much attention has been devoted to water’s metastable phase behavior, including polyamorphism (multiple amorphous solid phases), and the hypothesized liquid-liquid transition and associated critical point. However, the possible relationship between these phenomena remains incompletely understood. Using molecular dynamics simulations of the realistic TIP4P/2005 model, we found a striking signature of the liquid-liquid critical point in the structure of water glasses, manifested as a pronounced increase in long-range density fluctuations at pressures proximate to the critical pressure. By contrast, these signatures were absent in glasses of two model systems that lack a critical point. We also characterized the departure from equilibrium upon vitrification via the non-equilibrium index;water-like systems exhibited a strong pressure dependence in this metric, whereas simple liquids did not. These results reflect a surprising relationship between the metastable equilibrium phenomenon of liquid-liquid criticality and the non-equilibrium structure of glassy water, with implications for our understanding of water phase behavior and glass physics. Our calculations suggest a possible experimental route to probing the existence of the liquid-liquid transition in water and other fluids. © 2021, CC BY.

关键词： Criticality (nuclear fission)

Ethical Aspects of computational Modelling in Science, Decision Support and Communication 15th

学校读者我要写书评

暂无评论

Ethical Aspects of Computational Modelling in Science, Decis...

15th International Workshop on Artificial Life and Evolutionary Computation, WIVACE 2021

作者： Füchslin, Rudolf Marcel Ambühl, Jacques Faggian, Alessia Fellermann, Harold M. Flumini, Dandolo Geller, Armando Hanczyc, Martin M. Klinkert, Andreas Krütli, Pius Matuttis, Hans-Georg Ott, Thomas Scheidegger, Stephan Schmid, Gary Bruno Smieszek, Timo Schneider, Johannes J. Steiner, Albert Weyland, Mathias S. Institute of Applied Mathematics and Physics Zurich University of Applied Sciences Zurich Technikumstrasse 9 Winterthur8400 Switzerland European Centre for Living Technology Ca’ Bottacin Dorsoduro 3911 Calle Crosera Venice30123 Italy World Bank Group Geneva Switzerland University of Trento Trento38123 Italy School of Computing Newcastle University Science Square 1 Newcastle Upon TyneNE4 5TG United Kingdom GmbH Fraumünsterstrasse 11 Zurich8001 Switzerland Institute of Data Analysis and Process Design Zurich University of Applied Sciences Rosenstrasse 3 Winterthur8400 Switzerland Transdisciplinarity Lab ETH Zurich Zurich8092 Switzerland Department of Mechanical Engineering and Intelligent Systems The University of Electrocommunications Tokyo182-8585 Japan Institute of Computational Life Sciences Zurich University of Applied Sciences Schloss 1 Wädenswil8820 Switzerland Swiss NeuroCreations GmbH Hambergersteig 25 Zurich8008 Switzerland Muesmattweg 70 Allschwil4123 Switzerland

ISBN: (纸本)9783031239281

The development of data science, the increase of computational power, the availability of the internet infrastructure for data exchange and the urgency for an understanding of complex systems require a responsible and ethical use of computational models in science, communication and decision-making. Starting with a discussion of the width of different purposes of computational models, we first investigate the process of model construction as an interplay of theory and experimentation. We emphasise the different aspects of the tension between model variables and experimentally measurable observables. The resolution of this tension is a prerequisite for the responsible use of models and an instrumental part of using models in the scientific processes. We then discuss the impact of models and the responsibility that results from the fact that models support and may also guide experimentation. Further, we investigate the difference between computational modelling in an interdisciplinary science project and computational models as tools in transdisciplinary decision support. We regard the communication of model structures and modelling results as essential;however, this communication cannot happen in a technical manner, but model structures and modelling results must be translated into a "narrative." We discuss the role of concepts from disciplines such as literary theory, communication science, and cultural studies and the potential gains that a broader approach can obtain. Considering concepts from the liberal arts, we conclude that there is, besides the responsibility of the model author, also a responsibility of the user/reader of the modelling results. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Decision making

Multiple-relaxation-time discrete Boltzmann modeling of multicomponent mixture with nonequilibrium effects

学校读者我要写书评

暂无评论

Physical Review E 2021年第1期103卷 013305-013305页

作者： Chuandong Lin Kai H. Luo Aiguo Xu Yanbiao Gan Huilin Lai Sino-French Institute of Nuclear Engineering and Technology Sun Yat-Sen University Zhuhai 519082 China Department of Mechanical Engineering University College London Torrington Place London WC1E 7JE United Kingdom Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P. O. Box 8009-26 Beijing 100088 China State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology Beijing 100081 China Center for Applied Physics and Technology MOE Key Center for High Energy Density Physics Simulations College of Engineering Peking University Beijing 100871 China North China Institute of Aerospace Engineering Langfang 065000 China College of Mathematics and Informatics & FJKLMAA Fujian Normal University Fuzhou 350007 China

A multiple-relaxation-time discrete Boltzmann model (DBM) is proposed for multicomponent mixtures, where compressible, hydrodynamic, and thermodynamic nonequilibrium effects are taken into account. It allows the specific heat ratio and the Prandtl number to be adjustable, and is suitable for both low and high speed fluid flows. From the physical side, besides being consistent with the multicomponent Navier-Stokes equations, Fick's law, and Stefan-Maxwell diffusion equation in the hydrodynamic limit, the DBM provides more kinetic information about the nonequilibrium effects. The physical capability of DBM to describe the nonequilibrium flows, beyond the Navier-Stokes representation, enables the study of the entropy production mechanism in complex flows, especially in multicomponent mixtures. Moreover, the current kinetic model is employed to investigate nonequilibrium behaviors of the compressible Kelvin-Helmholtz instability (KHI). The entropy of mixing, the mixing area, the mixing width, the kinetic and internal energies, and the maximum and minimum temperatures are investigated during the dynamic KHI process. It is found that the mixing degree and fluid flow are similar in the KHI process for cases with various thermal conductivity and initial temperature configurations, while the maximum and minimum temperatures show different trends in cases with or without initial temperature gradients. Physically, both heat conduction and temperature exert slight influences on the formation and evolution of the KHI morphological structure.

关键词： Complex fluids Kelvin-Helmholtz instability Turbulent mixing

Optimizing the location of the colony of foragers with Collective Learning

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Bhowal, Sanchayan Samanta, Ramkrishna Jyoti Ray, Arnob Bhattacharyya, Sirshendu Hens, Chittaranjan Indian Statistical Institute Bangalore Centre 8th Mile Mysore Road Bangalore560 059 India Physics and Applied Mathematics Unit Indian Statistical Institute 203 B. T. Road Kolkata700108 India Department of Physics Raja Rammohun Roy Mahavidyalaya Radhanagar Hooghly 712406 India Center for Computational Natural Science and Bioinformatics International Institute of Informational Technology Gachibowli Hyderabad500032 India

Animal groups collaborate with one another throughout their lives to better comprehend their surroundings. Here, we try to model, using continuous random walks, how the entire process of birth, reproduction, and death might impact the searching process. We attempt to simulate an ecosystem where the post-reproductive foragers leave their colonies to discover where the targets are while others stay and breed at the base. Actually, a group of foragers searches for a location from where they access the targets for food supply. Particularly, we have explored a hypothetical situation in which the relocation to the new position depends on the agreement level of the species as well as an additional waiting time due to this agreement level. In this backdrop, detailed numerical results reveal that searching for an optimal position at an optimal mean time can be captured for a suitable range of the agreement level. We have also shown, for a given agreement level, the optimal mean time linearly increases with the Death-to-Birth ratio. Copyright © 2022, The Authors. All rights reserved.

关键词： Food supply

pynucastro: A Python Library for Nuclear Astrophysics

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Clark, Alexander Smith Johnson, Eric T. Chen, Zhi Eiden, Kiran Willcox, Donald E. Boyd, Brendan Cao, Lyra DeGrendele, Christopher J. Zingale, Michael Department of Physics and Astronomy Stony Brook University Stony BrookNY11794-3800 United States Department of Astronomy University of California Berkeley BerkeleyCA94720-3411 United States Center for Computational Sciences and Engineering Lawrence Berkeley National Lab United States Department of Astronomy Ohio State University ColumbusOH43210-1173 United States Department of Applied Mathematics University of California Santa Cruz Santa CruzCA95064-1077 United States

We describe pynucastro 2.0, an open source library for interactively creating and exploring astrophysical nuclear reaction networks. We demonstrate new methods for approximating rates and using detailed balance to create reverse rates, show how to build networks and determine whether they are appropriate for a particular science application, and discuss the changes made to the library over the past few years. Finally, we demonstrate the validity of the networks produced and share how we use pynucastro networks in simulation codes. Copyright © 2022, The Authors. All rights reserved.

关键词： Reaction rates

Discovery of smectic charge and pair-density-wave orders in topological monolayer 1T′-MoTe2

学校读者我要写书评

暂无评论

arXiv 2023年

作者： Wei, Li-Xuan Xiao, Peng-Cheng Li, Fangsen Wang, Li Deng, Bo-Yuan Cheng, Fang-Jun Zheng, Fa-Wei Hao, Ning Zhang, Ping Ma, Xu-Cun Xue, Qi-Kun Song, Can-Li State Key Laboratory of Low-Dimensional Quantum Physics Department of Physics Tsinghua University Beijing100084 China School of Physics and Physical Engineering Qufu Normal University Qufu273165 China Vacuum Interconnected Nanotech Workstation Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of Sciences Suzhou215123 China Key Lab of Advanced Optoelectronic Quantum Architecture and Measurement School of Physics Beijing Institute of Technology Beijing100081 China Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field Laboratory HFIPS Chinese Academy of Sciences Hefei230031 China Institute of Applied Physics and Computational Mathematics Beijing100088 China Frontier Science Center for Quantum Information Beijing100084 China Shenzhen Institute for Quantum Science and Engineering Department of Physics Southern University of Science and Technology Shenzhen518055 China Beijing Academy of Quantum Information Sciences Beijing100193 China

Symmetry-breaking phenomena are observed in numerous strongly-correlated systems including high-temperature superconductors. However, identifying these exotic phases and understanding their interplay with superconductivity in topological materials remain challenging. Here we employ a cryogenic scanning tunneling microscopy to discover a unidirectional (striped) charge order (CO) and a primary pair-density-wave (PDW) in topological monolayer 1T′-MoTe2. The two orders are spatially modulated uniaxially and share the same periodicity of five-unit cells or a wavevector QC ͌ QP ͌ (0, 0.4)π/b (b is the lattice constant along the Mo chains). Importantly, the primary PDW state features a two-gap superconductivity below the transition temperature of 6.0 K and induces another unique particle-hole-symmetric CO at twice the PDW wavevector. Combining these results and our density functional calculations, we reveal that the two striped orders are primarily driven by nesting behaviors between electron and hole pockets. Our findings establish monolayer 1T′-MoTe2 as a topological paradigm for exploring multiple preexisting symmetry-breaking states. © 2023, CC BY.

关键词： Monolayers

Evidence for eccentricity in the population of binary black holes observed by LIGO-Virgo-KAGRA

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Gupte, Nihar Ramos-Buades, Antoni Buonanno, Alessandra Gair, Jonathan Miller, M. Coleman Dax, Maximilian Green, Stephen R. Pürrer, Michael Wildberger, Jonas Macke, Jakob Romero-Shaw, Isobel M. Schölkopf, Bernhard Am Mühlenberg 1 Potsdam14476 Germany Department of Physics University of Maryland College ParkMD20742 United States Nikhef Science Park 105 Amsterdam1098 XG Netherlands Max Planck Institute for Intelligent Systems Max-Planck-Ring 4 Tübingen72076 Germany School of Mathematical Sciences University of Nottingham University Park NottinghamNG7 2RD United Kingdom Department of Physics East Hall University of Rhode Island KingstonRI02881 United States Center for Computational Research Carothers Library University of Rhode Island KingstonRI02881 United States Department of Applied Mathematics and Theoretical Physics CambridgeCB3 0WA United Kingdom Kavli Institute for Cosmology Cambridge Madingley Road CambridgeCB3 0HA United Kingdom

Binary black holes (BBHs) in eccentric orbits produce distinct modulations in the emitted gravitational waves (GWs). The measurement of orbital eccentricity can provide robust evidence for dynamical binary formation channels. We analyze 57 GW events from the first, second and third observing runs of the LIGO-Virgo-KAGRA (LVK) Collaboration using a multipolar aligned-spin inspiral-merger-ringdown waveform model with two eccentric parameters: eccentricity and relativistic anomaly. This is made computationally feasible with the machine-learning code DINGO, which accelerates inference by 2-3 orders of magnitude compared to traditional inference techniques. First, when using a uniform prior on the eccentricity, we find eccentric aligned-spin against quasi-circular aligned-spin log10 Bayes factors of 1.84 to 4.75 (depending on the glitch mitigation) for GW200129, 3.0 for GW190701 and 1.77 for GW200208 22. We measure egw, 10Hz to be 0.27+0.10−0.12 to 0.17+0.14−0.13 for GW200129, 0.35+0.32−0.11 for GW190701 and 0.35+0.18−0.21 for GW200208 22. Second, we find log10 Bayes factors between the eccentric aligned-spin versus quasi-circular precessing-spin hypothesis between 1.43 and 4.92 for GW200129, 2.61 for GW190701 and 1.23 for GW200208 22. Third, our analysis does not show evidence for eccentricity in GW190521, which has an eccentric aligned-spin against quasi-circular aligned-spin log10 Bayes factor of 0.04. Fourth, we estimate that if we neglect the spin-precession and use an astrophysically-motivated prior on the rate of eccentric BBHs, the probability of one out of the 57 events being eccentric is greater than 99.5% or (100 − 8.4 × 10−4)% (depending on the glitch mitigation). Fifth, we study the impact on parameter estimation when neglecting either eccentricity in quasi-circular models or higher modes in eccentric models for GW events. These results underscore the importance of including eccentric parameters in the characterization of BBHs for the upcoming observing runs

关键词： Black holes