检索结果-南通市图书馆

Density functional calculations of large systems containing heavy elements by means of the regionalization algorithm

引用

Science China Chemistry 2004年第6期47卷 453-465页

作者： HU Xiangqian LI Lemin State Key Laboratory of Rare Earth Materials and applications College of Chemistry and Molecular Engineering Peking University Beijing 100871 China State Key Laboratory of Rare Earth Materials and Applications College of Chemistry and Molecular Engineering Peking University Beijing 100871 China

The regionalized computational method is extended to the non-relativistic, scalar and 2-component relativistic density functional calculation of large systems containing transition series or heavy main-group metal elements. A large system is divided into several regions which can be considered as relatively independent quantum mechanical subsystems. Taking into account the Coulomb and exchange-correlation potentials as well as the Pauli repulsion exerted by the other subsystems, the Kohn-Sham equation related to subsystem K can be written as: $(F^K + F_P^K )C^K = S^K C^K \varepsilon ^K K = A,B,C \cdots ,$ where F K , C K , S K , ε K are the Fock matrix, the matrix of combination coefficients of orbitals, the overlap matrix of basis sets and the energy eigenvalue matrix, respectively. The matrix F K K reflects the Pauli repulsion from the other subsystems. F K may be non-relativistic, scalar or 2-component relativistic Fock matrix determined by the theoretical method related to the density functional calculations. The other matrices are mated with F K . Solving the Kohn-Sham equation for every subsystem and combining the results from the subsystem calculations, the electronic structural information of the whole system is derived. The density functional calculation of several molecules containing transition metal Ni or heavy main-group metal TI or Bi is performed by the afore-mentioned regionalization algorithm. The obtained results for each molecule are compared with those from the density functional calculation of that molecule in its entirety in order to check the feasibility of the regionalization algorithm. It is found that with sufficiently large regional basis set in the subsystem calculation the accuracy of the results calculated by the regionalization algorithm is essentially the same as that from the calculation of the molecule in its entirety. With proper smaller regional basis sets the accuracy of the results calculated with the regionalization algorithm c

关键词： density functional calculation, large system, transition metal, heavy element, regionalization algorithm.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

光滑粒子流体力学方法在流体、固体和生物力学中的应用

引用

Acta Mechanica Sinica 2023年第2期39卷 3-38页

作者：徐绯王佳怡杨扬王璐代震汉芮岐 School of Aeronautics Northwestern Polytechnical UniversityXi’an710072China Institute for computational Mechanics and Its applications Northwestern Polytechnical UniversityXi’an710072China School of Architecture and Engineering Chang’an UniversityXi’an710064China

光滑粒子流体动力学(smoothed particle hydrodynamics,SPH)作为最早发展的无网格粒子方法之一,对于模拟爆炸、冲击等涉及大变形问题,具有广阔的发展前景.本文对SPH方法在流体、固体和生物力学领域的改进算法和工程应用进行了全面介绍.... 详细信息

光滑粒子流体动力学(smoothed particle hydrodynamics,SPH)作为最早发展的无网格粒子方法之一,对于模拟爆炸、冲击等涉及大变形问题,具有广阔的发展前景.本文对SPH方法在流体、固体和生物力学领域的改进算法和工程应用进行了全面介绍.阐述了SPH的基本理论和高精度SPH改进算法,分析了流体、固体和生物力学领域的改进技术.在模拟流体问题时,采用δ-SPH和GSPH方法解决了流体不稳定性的问题,并且讨论了流固耦合中的界面接触方法.针对固体的数值模拟,总结了三种传统改进方法(如应力点法、守恒光滑法、人工应力法)和Total Lagrangian SPH方法,改善了拉伸不稳定性问题;在生物力学方面,阐述了SPH控制方程和相互作用力的计算方法.本文综述了近年来SPH方法的应用进展,包括复杂海洋工程中的流固耦合问题,固体领域的天体、岩土力学、爆炸冲击以及增材制造等工程应用和生物力学中血流动力学、肠道健康和植物生长等典型应用;并分析了国内外SPH软件的发展,介绍了多尺度自适应分辨率方法、并行计算方法和网格自动生成技术来克服数值模拟方法在计算效率和计算规模上的限制.最后对目前存在的问题进行总结与展望,包括提高SPH算法的数值精度、如何精确描述固体的损伤与断裂问题和计算精度与效率之间的平衡等.在未来研究中,建立多尺度耦合SPH模型和深度学习将是进一步拓宽SPH方法应用的重要方向.

关键词： Smoothed particle hydrodynamics High-accuracy algorithms Solid mechanics Biomechanics computational efficiency

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

A survey of the study of combinatorial batch code

引用

Frontiers of Mathematics in China 2023年第5期18卷 301-312页

作者： Dongdong JIA Yuebo SHEN Gengsheng ZHANG College of Mathematics and Information Science Hebei Normal UniversityShijiazhuang 050024China Information Department Children's Hospital of Hebei ProvinceShijiazhuang 050031China Hebei Key Laboratory of computational Mathematics and applications Shijiazhuang 050024China

A combinatorial batch code has strong practical motivation in the distributed storage and retrieval of data in a *** this survey,we give a brief introduction to the combinatorial batch codes and some progress.

关键词： Combinatorial batch codes optimal CBC uniform CBC set system

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nonequilibrium Green＇s function method for quantum thermal transport

引用

Frontiers of physics 2014年第6期9卷 673-697页

作者： Jian-Sheng Wangt Bijay Kumar Agarwalla Huanan Li Juzar Thingna Department of Physics and Centre for computational Science and Engineering National University of Singapore Singapore 117542 Republic of Singapore

This review deals with the nonequilibrium Green＇s function （NEGF） method applied to the problems of energy transport due to atomic vibrations （phonons）, primarily for small jtmction systems. We present a pedagogical introduction to the subject, deriving some of the well-known results such as the Laudauer-like formula for heat current in ballistic systerms. The main aim of the review is to build the machinery of the method so that it can be applied to other situations, which are not directly treated here. In addition to the above, we consider a nmnber of applications of NEGF, not in routine model system calculations, but in a few new aspects showing the power and usefulness of the formalism. In partkaflar, we discuss the problems of multiple leads, coupled left-right-lead system, and system without a center. We also apply the method to the problem of full counting statisties. In the case of nonlinear svstems, we make general comments on the thermal expansion effect. phonon relaxation timv. and a certain class of mean-field approximations. Lastly, we examine the relationship between NEGF. reduced density matrix, and master equation approaches to thermal transport,

关键词： nonequilibrium Green's function (NEGF) contour ordered Green's function thermal transport

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

CH_2,NH,and O heteroatom substitution effects on the electronic,optical,and charge transport properties of a 2,1,3-benzothiadiazole-based derivative:Insights from theory

引用

Science China Chemistry 2012年第7期55卷 1364-1369页

作者： HU Bo YAO Chan WANG QingWei ZHANG Hao YU JianKang Faculty of Chemistry Jilin Normal UniversitySiping 136000China Key Laboratory of Preparation and applications of Environmental Friendly Materials(Jilin Normal University) Ministry of EducationSiping 136000China State Key Laboratory of Theoretical and computational Chemistry Jilin UniversityChangchun 130023China Institute of Applied Physics and Technology Foundation Department of Liaoning Technical UniversityHuludao 123000China

A set of CH2-,NH-,and O-substituted 2,1,3-benzothiadiazole(BTD)-based derivatives have been investigated theoretically in order to explore their electronic,optical,and charge transport *** calculation results show that the electronic and optical properties of the pristine molecule can be easily tuned through changing the S substituent in the central aromatic *** on the calculated maximum emission wavelength,we predict that CH2-,NH-,and O-substituted BTD-based derivatives could be used as red,green,and orange light-emitting materials,*** CH2-,NH-or O-substitution,the oscillator strengths of the emission spectra are enhanced with respect to that of the pristine molecule,implying that these compounds have larger fluorescence ***,it can be deduced that CH2-,NH-,and O-substituted BTD-based derivatives may act as hole transport materials in organic light-emitting diodes.

关键词： organic light-emitting devices (OLEDs) 2 1 3-benzothiadiazole electronic properties optical properties reorganizationenergy

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

General solutions to a class of time fractional partial differential equations

引用

Applied Mathematics and Mechanics(English Edition) 2010年第7期31卷 815-826页

作者：黄凤辉郭柏灵 Department of Mathematics School of SciencesSouth China University of Technology Institute of Applied Physics and computational Mathematics

A class of time fractional partial differential equations is considered, which in- cludes a time fractional diffusion equation, a time fractional reaction-diffusion equation, a time fractional advection-diffusion equation, and their corresponding integer-order partial differential equations. The fundamental solutions to the Cauchy problem in a whole-space domain and the signaling problem in a half-space domain are obtained by using Fourier- Laplace transforms and their inverse transforms. The appropriate structures of the Green functions are provided. On the other hand, the solutions in the form of a series to the initial and boundary value problems in a bounded-space domain are derived by the sine- Laplace or cosine-Laplace transforms. Two examples are presented to show applications of the present technique.

关键词： fractional differential equation Caputo fractional derivative Green function Laplace transform Fourier transform sine (cosine) transform

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Light-induced magnetic phase transition in van der Waals antiferromagnets

引用

Science China(Physics,Mechanics & Astronomy) 2023年第7期66卷 136-141页

作者： Jiabin Chen Yang Li Hongyu Yu Yali Yang Heng Jin Bing Huang Hongjun Xiang Key Laboratory of computational Physical Sciences(Ministry of Education) Institute of Computational Physical SciencesState Key Laboratory of Surface PhysicsDepartment of PhysicsFudan UniversityShanghai 200433China Shanghai Qi Zhi Institute Shanghai 200030China Beijing computational Science Research Center Beijing 100193China Department of Physics Beijing Normal UniversityBeijing 100193China Collaborative Innovation Center of Advanced Microstructures Nanjing 210093China

Control over magnetic properties by optical stimulation is not only interesting from the physics point of view,but also important for practical applications such as magneto-optical ***,based on a simple tight-binding(TB)model,we propose a general theory of light-induced magnetic phase transition(MPT)in *** the fact that the bandgap of the antiferromagnetic(AFM)phase is usually larger than that of the ferromagnetic(FM)one for a given system,we suggest that light-induced electronic excitation prefers to stabilize the FM state over the AFM one,and will induce an MPT from AFM phase to FM phase once a critical photocarrier concentration(αc)is *** theory has been confirmed by performing firstprinciples calculations on a series of 2D van der Waals(vd W)***,a linear relationship betweenαc and the intrinsic material parameters is obtained,in agreement with our TB model *** general theory paves a new way to manipulate 2D magnetism with high speed and superior resolution.

关键词： first-principles calculation density functional theory two-dimensional materials magnetic phase transition

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Stark-Broadened Profiles of the Spectral Line P_α in He Ⅱ Ions

引用

Chinese Physics Letters 2016年第3期33卷 24-27页

作者：段斌 Muhammad Abbas Bari 吴泽清颜君王建国 Institute of Applied Physics and computational Mathematics Department of Physics and Applied Mathematics Pakistan Institute of Engineering and Applied Sciences

We report a systematic method to perform calculations of spectral line broadening parameters in plasmas. This method is applied to calculate Stark-broadening line profiles of Pα（n = 4 → n = 3） transitions under certain specific plasma conditions, by treating this case as an example. In the framework of the fully relativistic Dirac R- matrix theory, we calculate the electron-impact broadening operators, which are assumed to be diagonal matrix to simplify the situation. The electric microfield distribution function is calculated by retaining Hooper＇s formalism. The dipole matrix elements and atomic structure parameters used in these calculations have been obtained from atomic structure GRASP code. Based on this required data, we calculate the Stark-broadened line profiles of the Paschen spectral lines in He Ⅱ ions in a systematic manner. Overall, there is a very good agreement between our calculated Stark-broadened line profiles and other line Our reported spectral line-broadening data have real also play a fundamental role in plasma modeling. broadening numerical simulation codes （Sire U and MELS）. applications in plasma spectroscopy, plasma diagnosis and

关键词： Stark-Broadened Profiles of the Spectral Line P line on is II in He Ions of

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A fast multipole BEM for solving thin plate bending problems

A fast multipole BEM for solving thin plate bending problems

引用

中国力学大会——2013

作者： Liu Yijun Huang Shuo Mechanical Engineering University of Cincinnati Institute for computational Mechanics and Its applications(NPUiCMA) Northwestern Polytechnical University

A fast multipole boundary element method(BEM) for solving large-scale thin plate bending problems will be presented in this *** plate bending problems are governed by bihannonic equation under given boundary conditions. This PDE can be transformed into two direct boundary integral equations(BIEs) that are sufficient to solve the unknown boundary variables—deflection,rotation,shear force,or bending moment—two at each boundary *** multipole formulations are developed for the two direct BIEs based on the

关键词：

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Theoretical study of the electronic structures and spectroscopic properties of [(4'-XC≡Ctrpy)PtCl]^+ (trpy=2,2':6',2"-terpyridine;X=H,Me and Ph)

引用

Science China Chemistry 2009年第12期52卷 2226-2236页

作者： WANG Xin,BAI FuQuan,ZHOU Xin,LIU Tao & ZHANG HongXing State Key Laboratory of Theoretical and computational Chemistry,Institute of Theoretical Chemistry,Jilin University,Changchun 130023,China State Key Laboratory of Theoretical and computational Chemistry Institute of Theoretical Chemistry Jilin University Changchun China

The electronic structures and spectroscopic properties of [(4'-XC≡Ctrpy)PtCl]+(trpy = 2,2':6',2″-terpyridine; X = H (1),methyl (Me) (2),and phenyl (Ph) (3) were studied by the ab initio method. The structures at the ground and excited state were optimized at the B3LYP and CIS levels,respectively. The absorption and emission spectra in the dichloromethane solution were obtained by using the TD-DFT (B3LYP) method associated with the pcm model. The molecular orbital energy of the HOMOs of 1-3 with the d(Pt),p(Cl),π(trpy),and π(XC≡C) character is sensitive to the substituents on the acetylide ligand,but that of the trpy-based LUMOs with the π*(trpy) character varies slightly. The lowest lying emission at 503 nm for 1 is mainly attributed to the 3ILCT perturbed by the 3MLCT and 3LLCT transitions,but that at 535 nm for 2,and that at 558 nm for 3 are mainly attributed to the 3LLCT perturbed by the 3ILCT and 3MLCT transitions. The different electron-donating ability of H,Me,and Ph is responsible for the differences in emission character. Moreover,the calculation results show that the phosphorescent color can be turned by adjusting the substituents. Both the lowest energy absorption and emission of 1―3 are red-shifted in the order of 1<2<3,consistent with the electron-donating of H

关键词： platinum(Ⅱ) complexes TD-DFT absorption spectra charge transfer luminescence

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

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

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

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

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

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：