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Accurate Correlation Potentials from the Self-Consistent random Phase Approximation

Physical review Letters 2025年第1期134卷 016402-016402页

作者： Egor Trushin Steffen Fauser Andreas Mölkner Jannis Erhard Andreas Görling Lehrstuhl für Theoretische Chemie Universität Erlangen-Nürnberg Egerlandstraße 3 D-91058 Erlangen Germany Erlangen National High Performance Computing Center (NHR@FAU) Martensstraße 1 D-91058 Erlangen Germany

density-functional theory (dFT) within the Kohn-Sham (KS) formalism is the most widely used approach to treat electronic structures of molecules and solids in physics, chemistry, and materials science, and the development of more accurate functionals for the KS exchange and correlation energy has been a major research focus for decades. The corresponding exchange and correlation potentials, on the other hand, have attracted little attention. Those cases for which reference potentials are available showed that in particular correlation potentials from common approximate density functionals are of poor quality and sometimes have little in common with the exact potentials. This hampers the further development of KS-dFT. Here, we show that highly accurate correlation potentials can be obtained within the random phase approximation (rPA). In conjunction with the exact exchange potential, which, like the rPA correlation potential, is accessible within the optimized effective potential method, highly accurate exchange-correlation potentials are available and provide a basis for the further development of dFT. We present a numerically stable approach for efficiently carrying out self-consistent rPA calculations and combine it with a KS inversion method to obtain reference correlation potentials from highly accurate electron densities from coupled cluster calculations. Accurate exchange-correlation potentials have to yield KS eigenvalues for the highest occupied molecular orbital that are close to the negative of the ionization potential. This is indeed the case, the rPA highest occupied molecular orbital eigenvalues yield ionization potentials that can compete with GW ionization potentials.

关键词： Molecular orbitals

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robust Integration of Fast Flavor Conversions in Classical Neutrino Transport

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Physical review Letters 2025年第5期134卷 051003-051003页

作者： Zewei Xiong Meng-ru Wu Manu George Chun-Yu Lin GSI Helmholtzzentrum für Schwerionenforschung Planckstraße 1 64291 Darmstadt Germany Institute of Physics Academia Sinica Taipei 115201 Taiwan Institute of Astronomy and Astrophysics Academia Sinica Taipei 106319 Taiwan Physics Division National Center for Theoretical Sciences Taipei 106319 Taiwan National Center for High-performance Computing Hsinchu 30076 Taiwan

The quantum kinetic evolution of neutrinos in dense environments, such as the core-collapse supernovae or the neutron star mergers, can result in fast flavor conversion (FFC), presenting a significant challenge to achieving robust astrophysical modeling of these systems. recent works that directly simulate the quantum kinetic transport of neutrinos in localized domains have suggested that the asymptotic outcome of FFCs can be modeled by simple analytical prescriptions when coarse grained over a size much larger than the FFC length scale. In this Letter, by leveraging such a scale separation, we incorporate the analytical prescriptions into global simulations that solve the classical neutrino transport equation including collisions and advection under spherical symmetry. We demonstrate that taking this approach allows to obtain results that quantitatively agree with those directly from the corresponding global quantum kinetic simulations and precisely capture the collisional feedback effect for cases where the FFC happens inside the neutrinosphere. Notably, the effective scheme does not require resolving the FFC time and length scales, hence only adds negligible computational overhead to classical transport. Our work highlights that efficient and robust integration of FFCs in classical neutrino transport used in astrophysical simulation can be feasible.

关键词： Supernovae

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Timing-Sequence Testing of Parallel Programs

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Journal of Computer Science & Technology 2000年第1期15卷 84-95页

作者：梁煜李舒张辉韩承德 Center of High-Performance Computing Institute of Computing Technology Chinese Academy of Sciences Beijing P.R. China

Testing of parallel programs involves two parts-testing of controlflow within the processes and testing of timing-sequence. This paper focuses on thelatter, particularly on the timing-sequence of message-passing paradigms. Firstlythe coarse-grained SYN-sequence model is built up to describe the execution of distributed programs. All of the topics discussed in this paper are based on it. Themost direct way to test a program is to run it. A fault-free parallel program shouldbe of both correct computing results and proper SYN-sequence. In order to analyzethe validity of observed SYN-sequence, this paper presents the formal specification(Backus Normal Form) of the valid SYN-sequence. Till now there is little workabout the testing coverage for distributed programs. Calculating the number of thevalid SYN-sequences is the key to coverage problem, while the number of the validSYN-sequences is terribly large and it is very hard to obtain the combination lawamong SYN-events. In order to resolve this problem, this paper proposes an efficienttesting strategy- atomic SYN-event testing, which is to linearize the SYN-sequence(making it only consist of serial atomic SYN-events) first and then test each atomicSYN-event independently. This paper particularly provides the calculating formulaabout the number of the valid SYN-sequences for tree-topology atomic SYN-event(broadcast and combine). Furthermore, the number of valid SYN-sequences also,to some degree, mirrors the testability of parallel programs. Taking tree-topologyatomic SYN-event as an example, this paper demonstrates the testability and communication speed of the tree-topology atomic SYN-event under different numbersof branches in order to achieve a more satisfactory tradeoff between testability andcommunication efficiency.

关键词： timing-sequence testing SYN-sequence atomic SYN-event linearization coverage

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A Fast Algorithm for Mining Association rules

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Journal of Computer Science & Technology 2000年第6期15卷 619-624页

作者：黄刘生陈华平王洵陈国良 National High Performance Computing Center Department of Computer Science University of Science & Technology of China Hefei P.R. China

In this paper, the problem of discovering association rules between items in a large database of sales transactions is discussed, and a novel algorithm, BitMatrix, is proposed. The proposed algorithm is fundamentally different from the known algorithms Apriori and AprioriTid. Empirical evaluation shows that the algorithm outperforms the known ones for large databases. Scale-up experiments show that the algorithm scales linearly with the number of transactions.

关键词： database data mining large itemset association rule minimum support minimum confidence

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Low-Overhead Non-Blocking Checkpointing Scheme for Mobile computing Systems

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Tsinghua Science and Technology 2007年第S1期12卷 110-115页

作者：门朝光曹刘娟王立闻徐振朋 R & D Center of High Dependability Computing Technology Harbin Engineering University

When applied to mobile computing systems,checkpoint protocols for distributed computing systems would face many new challenges, such as low wireless bandwidth, frequent disconnections, and lack of stable storage at mobile hosts. This paper proposes a novel checkpoint protocol to effectively reduce the coordinating overhead. By using a communication vector, only a few processes participate in the checkpointing event. during checkpointing, the scheme can save the time used to trace the dependency tree by sending checkpoint requests to dependent processes at once. In addition, processes are non- blocking in this scheme, since the inconsistency is resolved by the piggyback technique. Hence the unnecessary and orphan messages can be avoided. Compared with the traditional coordinated checkpoint approach, the proposed non-blocking algorithm obtains a minimal number of processes to take checkpoints. It also reduces the checkpoint latency, which brings less overhead to mobile host with limited resources.

关键词： mobile computing fault tolerant coordinated checkpoint rollback recovery

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Optimal Bandwidth Utilization of All—Optical ring with a Converter of degree 4

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Journal of Computer Science & Technology 2002年第4期17卷 411-419页

作者：许胤龙陈国良黄刘生万颖瑜 Department of Computer Science and Technology University of Science and Technology of China National High Performance Computing Center at Hefei Hefei 230027 P.R. China

In many models of all-optical routing, a set of communication paths in a network is given, and a wavelength is to be assigned to each path so that paths sharing an edge receive different wavelengths. The goal is to assign as few wavelengths as possible, in order to use the optical bandwidth efficiently. If a node of a network contains a wavelength converter,any path that passes through this node may change its wavelength. Having converters at some of the nodes can reduce the number of wavelengths required for routing. This paper presents a wavelength converter with degree 4 and gives a routing algorithm which shows that any routing with load L can be realized with L wavelengths when a node of an all-optical ring hosts such a wavelength converter. It is also proved that 4 is the minimum degree of the converter to reach the full utilization of the available wavelengths if only one node of an all-optical ring hosts a converter.

关键词： all-optical network ring wavelength assignment wavelength translation

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An efficiency way for sharing real-time data and the application of remote network video system

An efficiency way for sharing real-time data and the applica...

引用

9th IEEE International Workshop on Cellular Neural Networks and their Applications, CNNA

作者： Wu, Jyh-Horng Lien, Ho-Cheng Huang, Chen-Pey Shiau, Yi-Haur Tsai, Whey-Fone National Center for High-Performance Computing 7 R and D Road VI Science Park Hsinchu 300 Taiwan

This study is to integrate the current monitoring systems and to develop the multicasting and peer-to-peer network environment for end users. Because the bandwidth of network is limited where the camera is located, the transmission of images will delay or crash when over a few numbers of end user login simultaneously. In this paper, the middleware for sharing real-time data will be developed to solve the problem of limitation for multi-connection from fields. The monitoring systems for flood events, that are located in the rivers, creeks, reservoirs, and pump stations of Taiwan, will be integrated as a demo case to show the capability of the system integration. And in this case will also show how the performance is that sharing real-time data for unlimited number of users with limited network bandwidth.

关键词： Image processing

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ddSF: A data deduplication system framework for cloud environments

DDSF: A data deduplication system framework for cloud enviro...

引用

4th International Conference on Cloud computing and Services Science, CLOSEr 2014

作者： Gu, Jianhua Zhang, Chuang Zhang, Wenwei High Performance Computing R and D Center School of Computer Science and Technology Northwestern Polytechnical University Xi'an China

ISBN: (纸本)9789897580192

Cloud storage has been widely used because it can provide seemingly unlimited storage space and flexible access way, while the rising cost of storage and communications is an issue. In this paper, we propose a data deduplication System Framework(ddSF) for cloud storage environments. The ddSF consists of three major components, the client, fingerprint server and storage component. The client component divides file into chunks and calculates hash value of each chunk. And it only sends the chunk whose hash value has not existed in fingerprint server component to the storage component, so it can reduce consumption of communications and storage space. We developed an Index File System(IFS) to manage the metadata of user file in fingerprint server. The fingerprint server component maintains a hash table containing the hash values of chunks already stored in storage component. This paper presents a two-level indexing mechanism to improve the both spatial and temporal overhead to access to the hash table. The first level employs the Bloom Filter and the second level uses hash table partition mechanism. In order to reduce the possibility of accidental collision of data block hash value, we use two hash algorithms to calculate the hash value of the chunk. We further conduct some experiments in our framework. The results of these experiments demonstrate that framework proposed in this paper can improve storage space utilization and reduce consumption of communications. Copyright © 2014 SCITEPrESS - Science and Technology Publications.

关键词： Cloud storage

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Sustained Simulation performance 2017 1

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1000年

作者： Michael M. resch Wolfgang Bez Erich Focht Michael Gienger Hiroaki Kobayashi

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reconstructing the dark energy density in light of dESI BAO observations

arXiv

引用

arXiv 2025年

作者： Berti, Maria Bellini, Emilio Bonvin, Camille Kunz, Martin Viel, Matteo Zumalacarregui, Miguel Département de Physique Théorique Center for Astroparticle Physics Université de Genève Quai E. Ansermet 24 Genève 4CH-1211 Switzerland Center for Astrophysics and Cosmology University of Nova Gorica Nova Gorica Slovenia INAF Istituto Nazionale di Astrofisica Osservatorio Astronomico di Trieste Via G. B. Tiepolo 11 TriesteI-34131 Italy IFPU Institute for Fundamental Physics of the Universe via Beirut 2 TriesteI-34151 Italy SISSA - International School for Advanced Studies Via Bonomea 265 TriesteI-34136 Italy INFN – National Institute for Nuclear Physics Via Valerio 2 TriesteI-34127 Italy Italian Research Center on High Performance Computing Big Data and Quantum Computing Italy Am Mühlenberg 1 Potsdam-GolmD-14476 Germany

In light of the evidence for dynamical dark energy (dE) found from the most recent dark Energy Spectroscopic Instrument (dESI) baryon acoustic oscillation (BAO) measurements, we perform a non-parametric, model-independent reconstruction of the dE density evolution. To do so, we develop and validate a new framework that reconstructs the dE density through a third-degree piece-wise polynomial interpolation, allowing for direct constraints on its redshift evolution without assuming any specific functional form. The strength of our approach resides in the choice of directly reconstructing the dE density, which provides a more straightforward relation to the distances measured by BAO than the equation of state parameter. We investigate the constraining power of cosmic microwave background (CMB) observations combined with supernovae (SNe) and BAO measurements. In agreement with results from other works, we find a preference for deviations from ΛCdM, with a significance of 2.4σ when using the dark Energy Survey Year 5 (dESY5) SNe data, and 1.3σ with PantheonPlus. In all the cases we consider, the derived dE equation of state parameter presents evidence for phantom crossing. By investigating potential systematic effects in the low-redshift samples of dESY5 observations, we confirm that correcting for the offset in apparent magnitude with respect to PantheonPlus data, as suggested in previous studies, completely removes the tension. Furthermore, we assess the risk of potentially overfitting the data by changing the number of interpolation nodes. As expected, we find that with lesser nodes we get a smoother reconstructed behavior of the dE density, although with similar overall features. The pipeline developed in this work is ready to be used with future high-precision data to further investigate the evidence for a non-standard background evolution. Copyright © 2025, The Authors. All rights reserved.

关键词： Supernovae

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