检索结果-内蒙古大学图书馆

Specialising neural network potentials for accurate properties and application to the mechanical response of titanium

引用

npj computational Materials 2021年第1期7卷 1908-1918页

作者： Tongqi Wen Rui Wang Lingyu Zhu Linfeng Zhang Han Wang David J.Srolovitz Zhaoxuan Wu Department of Materials Science and Engineering City University of Hong KongKowloonHong KongSARChina Hong Kong Institute for Advanced Study City University of Hong KongKowloonHong KongSARChina Beijing Institute of Big Data Research BeijingChina Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijingChina Department of Mechanical Engineering The University of Hong KongHong KongSARChina International Digital Economy Academy(IDEA) ShenzhenChina

Large scale atomistic simulations provide direct access to important materials phenomena not easily accessible to experiments or quantum mechanics-based calculation *** and efficient interatomic potentials are the key enabler,but their development remains a challenge for complex materials and/or complex *** learning potentials,such as the Deep Potential(DP)approach,provide robust means to produce general purpose interatomic ***,we provide a methodology for specialising machine learning potentials for high fidelity simulations of complex phenomena,where general potentials do not *** an example,we specialise a general purpose DP method to describe the mechanical response of two allotropes of titanium(in addition to other defect,thermodynamic and structural properties).The resulting DP correctly captures the structures,energies,elastic constants andγ-lines of Ti in both the HCP and BCC structures,as well as properties such as dislocation core structures,vacancy formation energies,phase transition temperatures,and thermal *** DP thus enables direct atomistic modelling of plastic and fracture behaviour of *** approach to specialising DP interatomic potential,DPspecX,for accurate reproduction of properties of interest“X”,is general and extensible to other systems and properties.

关键词： titanium enable neural

来源：评论

学校读者我要写书评

暂无评论

Isotope effects in x-ray absorption spectra of liquid water

引用

Physical Review B 2020年第11期102卷 115155-115155页

作者： Chunyi Zhang Linfeng Zhang Jianhang Xu Fujie Tang Biswajit Santra Xifan Wu Department of Physics Temple University Philadelphia Pennsylvania 19122 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA

The isotope effects in x-ray absorption spectra of liquid water are studied by a many-body approach within electron-hole excitation theory. The molecular structures of both light and heavy water are modeled by path-integral molecular dynamics based on the advanced deep-learning technique. The neural network is trained on ab initio data obtained with SCAN density functional theory. The experimentally observed isotope effect in x-ray absorption spectra is reproduced semiquantitatively in theory. Compared to the spectrum in normal water, the blueshifted and less pronounced pre- and main-edge in heavy water reflect that the heavy water is more structured at short- and intermediate-range of the hydrogen-bond network. In contrast, the isotope effect on the spectrum is negligible at post-edge, which is consistent with the identical long-range ordering in both liquids as observed in the diffraction experiment.

关键词： Atomic & molecular structure Electronic excitation & ionization Water Density functional calculations Electronic structure First-principles calculations Machine learning Molecular dynamics X-ray absorption spectroscopy

来源：评论

学校读者我要写书评

暂无评论

Neural network representation of electronic structure from ab initio molecular dynamics

引用

Science Bulletin 2022年第1期67卷 29-37,M0003页

作者： Qiangqiang Gu Linfeng Zhang Ji Feng International Center for Quantum Materials School of PhysicsPeking UniversityBeijing 100871China Department of Mathematics and Program in Applied and Computational Mathematics Princeton UniversityPrincetonNJ 08544USA Collaborative Innovation Center of Quantum Matter Beijing 100871China

Despite their rich information content,electronic structure data amassed at high volumes in ab initio molecular dynamics simulations are generally *** introduce a transferable high-fidelity neural network representation of such data in the form of tight-binding Hamiltonians for crystalline *** predictive representation of ab initio electronic structure,combined with machinelearning boosted molecular dynamics,enables efficient and accurate electronic evolution and *** it is applied to a one-dimension charge-density wave material,carbyne,we are able to compute the spectral function and optical conductivity in the canonical *** spectral functions evaluated during soliton-antisoliton pair annihilation process reveal significant renormalization of low-energy edge modes due to retarded electron-lattice coupling beyond the Born-Oppenheimer *** availability of an efficient and reusable surrogate model for the electronic structure dynamical system will enable calculating many interesting physical properties,paving the way to previously inaccessible or challenging avenues in materials modeling.

关键词： Neural network Tight-binding model Electronic structure ab initio molecular dynamics

来源：评论

学校读者我要写书评

暂无评论

New features and enhancements of reactor Monte Carlo code RMC

New features and enhancements of reactor Monte Carlo code RM...

引用

mathematics and Computations, Supercomputing in Nuclear Applications and Monte Carlo International Conference, M and C+SNA+MC 2015

作者： Wang, Kan Liang, Jingang Yu, Jiankai Fan, Xiao Qiu, Yishu Liu, Shichang Yang, Feng Shang, Xiaotong Wu, Gaochen Shen, Qicang Yexin, Ouwen Chen, Zonghuan Yu, Ganglin Xu, Qi She, Ding Li, Zeguang Li, Songyang Department of Engineering Physics Tsinghua University Beijing100084 China Institute of Applied Physics and Computational Mathematics Beijing China Institute of Nuclear and New Energy Technology Tsinghua University Beijing China

ISBN: (纸本)9781510808041

This paper is to summarize the new features and enhancements of Reactor Monte Carlo code RMC. Random number generator's period has been extended to 2126 by implementing 128-bit integer multiplication based on Linear Congruential Algorithm. On-the-fly Doppler broadening methods are explored in two feasible ways, i.e., pre-Doppler broadening before transport calculations and stochastic sampling Doppler broadening based on Maxwell Boltzmann distribution for the target nuclei agitation. Three approaches including Random Lattice Method, Chord Length Sampling and explicit modeling with mesh acceleration are implemented in RMC for stochastic medium simulations. Photon transport is added and photon-neutron coupling transport calculations are achieved for broader applications of RMC. Iterated fission probability (IFP) method and Wielandt method are employed to make RMC having the capabilities of sensitivity and uncertainty analysis. RMC is approaching 3D full core burnup calculations with combined tally and depletion data decomposition. The kinetics simulation capability is implemented in RMC based on the predictor-corrector quasi-static method. Copyright © (2015) by the American Nuclear Society All rights reserved.

关键词： Stochastic systems

来源：评论

学校读者我要写书评

暂无评论

Generalised Error Functions from the Kerr Metric

引用

Chinese physics Letters 2016年第3期33卷 12-16页

作者：唐文林罗子人刘润球 Science and Technology on Aerospace Flight Dynamics Laboratory Beijing Aerospace Control Center Department of Aerospace Guidance Navigation and Control School of AstronauticsBeihang University QUEST Center of Quantum Engineering and Space-Time Research Leibniz Universitt Hannover Max Planck Institute for Gravitational Physics(Albert Einstein Institute) Institute of Applied Mathematics Morningside Center of Mathematics and LESCInstitute of Computational MathematicsAcademy of Mathematics and System ScienceChinese Academy of Sciences

Motivated by the effort to understand the mathematical structure underlying the Teukolsky equations in a Kerr metric background, a homogeneous integral equation related to the prolate spheroidal function is studied. From the consideration of the Fredholm determinant of the integral equation, a family of generalized error function is defined, with which the Fredholm determinant of the sinc kernel is also evaluated. An analytic solution of a special ease of the fifth Painlev~ transcendent is then worked out explicitly.

关键词： of is exp in Generalised Error Functions from the Kerr Metric from

来源：评论

学校读者我要写书评

暂无评论

Preparation of pseudo-pure states for NMR quantum computing with one ancillary qubit

引用

Science China(physics,Mechanics & Astronomy) 2019年第6期62卷 13-20页

作者： Tao Xin Liang Hao Shi-Yao Hou Guan-Ru Feng Gui-Lu Long State Key Laboratory of Low-dimensional Quantum Physics and Department of Physics Tsinghua University Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology Center for Quantum Computing Peng Cheng Laboratory Shenzhen Key Laboratory of Quantum Science and Engineering Southern University of Science and Technology Institute of Applied Physics and Computational Mathematics Center for Computational Sciences Sichuan Normal University College of Physics and Electronic Engineering Sichuan Normal University Institute for Quantum Computing Waterloo Tsinghua National Laboratory of Information Science and Technology The Innovative Center of Quantum Matter

Quantum state preparation plays an equally important role as quantum operations and measurements in quantum information processing. The previous methods for initialization require either an exponential number of experiments, or cause signal reduction or place restrictions on molecular structures. In this study, we propose three types of quantum circuits for preparing the pseudo-pure states of(n-1) qubits in the n-coupled Hilbert space, which simply needs the assistance of one ancilla spin and two different experiments independent of n. Most importantly, our methods work well on homo-nuclear and hetero-nuclear molecules without the reduction of signals in the gradient field. As a proof-of-principle demonstration, we experimentally prepared the pseudo-pure states of heteronuclear 2-qubit and homonuclear 4-qubit molecules using a nuclear magnetic resonance quantum information processor.

关键词： quantum state preparation nuclear magnetic resonance quantum algorithms

来源：评论

学校读者我要写书评

暂无评论

Variational boundary conditions for molecular dynamics simulations of crystalline solids at finite temperature: Treatment of the thermal bath

引用

Physical Review B 2007年第10期76卷 104107-104107页

作者： Xiantao Li Weinan E Department of Mathematics and Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA

This paper presents a systematic approach for finding efficient boundary conditions for molecular dynamics simulations of crystalline solids. These boundary conditions effectively eliminate phonon reflection at the boundary and at the same time allow the thermal energy from the bath to be introduced to the system. Our starting point is the Mori-Zwanzig formalism [R. Zwanzig, J. Chem. Phys. 32, 1173 (1960); in Systems Far from Equilibrium, edited by L. Garrido (Interscience, New York, 1980); H. Mori, Prog. Theor. Phys. 33, 423 (1965)] for eliminating the thermal bath, but we take the crucial next step that goes beyond this formalism in order to obtain memory kernels that decay faster. An equivalent variational formulation allows us to find the optimal approximate boundary conditions, after specifying the spatial-temporal domain of dependence for the positions of the boundary atoms. Application to a one-dimensional chain, a two-dimensional Lennard-Jones system, and a three-dimensional model of α-iron with embedded atom potential is presented to demonstrate the effectiveness of this approach.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Analysis of Sparse Quasi-Newton Updates with Positive Definite Matrix Completion

引用

Journal of the Operations Research Society of China 2014年第1期2卷 39-56页

作者： Yu-Hong Dai Nobuo Yamashita State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics and Scientific/Engineering ComputingAcademy of Mathematics and Systems ScienceChinese Academy of SciencesP.O.Box 2719Beijing 100080People’s Republic of China Department of Applied Mathematics and Physics Graduate School of InformaticsKyoto UniversityKyoto 606-8501Japan

Based on the idea of maximum determinant positive definite matrix completion,Yamashita(Math Prog 115(1):1–30,2008)proposed a new sparse quasi-Newton update,called MCQN,for unconstrained optimization problems with sparse Hessian *** exchange of the relaxation of the secant equation,the MCQN update avoids solving difficult subproblems and overcomes the ill-conditioning of approximate Hessian ***,local and superlinear convergence results were only established for the MCQN update with the DFP *** this paper,we extend the convergence result to the MCQN update with the whole Broyden’s convex *** results are also reported,which suggest some efficient ways of choosing the parameter in the MCQN update the Broyden’s family.

关键词： Quasi-Newton method Large-scale problems Sparsity Positive definite matrix completion Superlinear convergence

来源：评论

学校读者我要写书评

暂无评论

Efficient Numerical Algorithm for Large-Scale Damped Natural Gradient Descent

arXiv

引用

arXiv 2023年

作者： Chen, Yixiao Xie, Hao Wang, Han Program in Applied and Computational Mathematics Princeton University United States Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics

We propose a new algorithm for efficiently solving the damped Fisher matrix in large-scale scenarios where the number of parameters significantly exceeds the number of available samples. This problem is fundamental for natural gradient descent and stochastic reconfiguration. Our algorithm is based on Cholesky decomposition and is generally applicable. Benchmark results show that the algorithm is significantly faster than existing methods. Copyright © 2023, The Authors. All rights reserved.

关键词： Stochastic systems

来源：评论

学校读者我要写书评

暂无评论

Matrix-Free physics-Based Preconditioned Krylov Subspace Methods for 2D Particle Transport Problem

Matrix-Free Physics-Based Preconditioned Krylov Subspace Met...

引用

第十六届全国流体力学数值方法研讨会2013

作者： Tong-Xiang Gu Yan-Hua Cao Mao-Sheng Li Xing-Ping Liu Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Department of Mathematics North China Electric Power University Research Center of Magnetic Driven Fusion Institute of Applied Physics and Computational Mathematics

Source iteration is a iterative process usually used to solve the particle transport problem. For physical system containing subregions that are optically thick and scattering-dominated, most of the particles undergo ... 详细信息

关键词： Particle transport Matrix-free physics-based preconditioner Krylov subspace method Source iteration

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：