检索结果-内蒙古大学图书馆

Molecular Dynamics simulation of Aerogel Silica on Parallel Computers

MRS Online Proceedings Library 2020年第1期293卷 237-242页

作者： Aiichiro Nakano Rajiv K. Kalia Priya Vashishta Concurrent Computing Laboratory for Materials Simulations Department of Physics & Astronomy and Department of Computer Science Louisiana State University Baton Rouge USA

Molecular dynamics (MD) simulations of porous silica, in the density range 2.2 - 0.1 g/cm3, are carried out on a 41,472 particle system using two- and three-body interatomic potentials. Calculated results for fractal dimension and small-angle neutron scattering data are in good agreement with neutron scattering experiments. Results for structural correlations reveal crossovers from the short- to intermediate range (< 8 Å) and fractal to large-scale regime (10 ~ 100 Å). The MD program simulations are carried out on distributed-memory MIMD computers using a domain-decomposition algorithm. The algorithm employs the linked-cell- list method and separable three-body force calculation. The force calculation is accelerated by the multiple-time-step method. The parallel algorithm is highly efficient (parallel efficiency = 0.974), as it involves only 3 % communication overhead.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Structural and Dynamical Correlations in Stishovite and High Density Silica Glass

引用

MRS Online Proceedings Library 2020年第1期293卷 247-252页

作者： Wei Jin Rajiv K. Kalia Priya Vashishta Concurrent Computing Laboratory for Materials Simulations Department of Physics & Astronomy and Department of Computer Science Louisiana State University Baton Rouge USA

Pressure-induced structural transformation from tetrahedral to octahedral coordination and the destruction of intermediate-range order (IRO) are studied in silica glass (a-SiO2) using the molecular-dynamics (MD) method. Changes in the position and height of the first sharp diffraction peak (FSDP) in the static structure factor, bond lengths, coordination numbers, bond-angle distributions, and statistics of rings are investigated as a function of density. Modifications of the vibrational density of states and participation ratio are also discussed.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Structure and Dynamics of Network Glasses at Large Positive and Negative Pressures - A Molecular Dynamics Study

引用

MRS Online Proceedings Library 2020年第1期293卷 225-236页

作者： Priya Vashishta Rajiv K. Kalia Concurrent Computing Laboratory for Materials Simulations Department of Physics & Astronomy and Department of Computer Science Louisiana State University Baton Rouge USA

Using the molecular dynamics (MD) method, the nature of crystalline fragments in SiSe2 glass (a-SiSe2) at normal pressure, structural transformation and the loss of intermediate range order in SiO2 glass at very large positive pressures, and the modification of SiO2 glass network at very large negative pressures have been investigated. Implementations of the MD algorithm on the Connection Machine and Intel iPSC/860 machine are discussed. We investigate the nature of tetrahedral-molecular fragments in a-SiSe2. MD simulations reveal that the glass consists of both edge-sharing and corner-sharing tetrahedra. Edge-sharing tetrahedra are the building blocks of 10–15 Å long tetrahedral fragments where two-edge-sharing tetrahedra are the nucleus and comer-sharing configurations provide the connecting hinges between the molecular fragments. Pressure-induced structural transformation in a-SiO2 is investigated with the MD method. At high densities, the height of the first sharp diffraction peak in the static structure factor is considerably diminished, its position shifts to larger wave vectors, and a new peak appears at ~2.85 Å−1. At twice the normal density, Si-O bond length increases, Si-O coordination changes from 4 to 6, and O-Si-O band-angle changes from 109° to 90°. This is clearly a tetrahedral to octahedral transformation, which is observed recently by Meade, Hemley, and Mao in their diffraction experiments using synchrotron radiation. MD simulations of porous silica are carried out in the density range 2.2 - 0.1 g/cm3. Internal surface area, pore surface-to-volume ratio, gyration radius, and fractal dimension are studied as a function of density. simulation results are in good agreement with experimental results obtained by x-ray scattering experiments. The result reveals a crossover of the structural correlations between short- to intermediate-range (< 8 Å) and fractal- to large- scale-regime (10 ~ 100 Å). MD is a numerical approach which involves the solution of N

关键词：

来源：评论

学校读者我要写书评

暂无评论

Oxidation Dynamics of Nanophase Aluminum Clusters: A Molecular Dynamics Study

引用

MRS Online Proceedings Library 2020年第1期481卷 625-630页

作者： Ogata, Shuji Campbell, Timothy J. Tsuruta, Kenji Nakano, Aiichiro Kalia, Rajiv K. Vashishta, Priya Loong, Chun-K. Department of Applied Sciences Yamaguchi University Ube Japan Concurrent Computing Laboratory for Materials Simulations Department of Physics and Astronomy Department of Computer Science Louisiana State University Baton Rouge Argonne National Laboratory Argonne

Oxidation of an aluminum nanocluster (252,158 atoms) of radius 100Å placed in gaseous oxygen (530,727 atoms) is investigated by performing molecular-dynamics simulations on parallel computers. The simulation takes into account the effect of charge transfer between Al and 0 based on the electronegativity equalization principles. We find that the oxidation starts at the surface of the cluster and the oxide layer grows to a thickness of ∼28Å. Evolutions of local temperature and densities of Al and 0 are investigated. The surface oxide melts because of the high temperature resulting from the release of energy associated with Al-O bondings. Amorphous surface-oxides are obtained by quenching the cluster. Vibrational density-of-states for the surface oxide is analyzed through comparisons with those for crystalline Al, Al nanocluster, and α-Al2O3

关键词：

来源：评论

学校读者我要写书评

暂无评论

Quantum simulation for High-Energy physics

引用

PRX Quantum 2023年第2期4卷 027001-027001页

作者： Christian W. Bauer Zohreh Davoudi A. Baha Balantekin Tanmoy Bhattacharya Marcela Carena Wibe A. de Jong Patrick Draper Aida El-Khadra Nate Gemelke Masanori Hanada Dmitri Kharzeev Henry Lamm Ying-Ying Li Junyu Liu Mikhail Lukin Yannick Meurice Christopher Monroe Benjamin Nachman Guido Pagano John Preskill Enrico Rinaldi Alessandro Roggero David I. Santiago Martin J. Savage Irfan Siddiqi George Siopsis David Van Zanten Nathan Wiebe Yukari Yamauchi Kübra Yeter-Aydeniz Silvia Zorzetti Physics Division Lawrence Berkeley National Laboratory Berkeley California 94720 USA Department of Physics Maryland Center for Fundamental Physics and the NSF Institute for Robust Quantum Simulation University of Maryland College Park Maryland 20742 USA Department of Physics University of Wisconsin Madison Wisconsin 53706 USA T-2 Los Alamos National Laboratory Los Alamos New Mexico 87545 USA Fermi National Accelerator Laboratory Batavia Illinois 60510 USA Enrico Fermi Institute University of Chicago Chicago Illinois 60637 USA Kavli Institute for Cosmological Physics University of Chicago Chicago Illinois 60637 USA Department of Physics University of Chicago Chicago Illinois 60637 USA Department of Physics and Illinois Center for the Advanced Study of the Universe and Illinois Quantum Information Science and Technology Center University of Illinois Urbana Illinois 61801 USA QuEra Computing Inc Boston Massachusetts 02135 USA Department of Mathematics University of Surrey Guildford Surrey GU2 7XH United Kingdom Center for Nuclear Theory Department of Physics and Astronomy Stony Brook University New York 11794-3800 USA Department of Physics Brookhaven National Laboratory Upton New York 11973 USA Peng Huanwu Center for Fundamental Theory Hefei Anhui 230026 China Interdisciplinary Center for Theoretical Study University of Science and Technology of China Hefei Anhui 230026 China Pritzker School of Molecular Engineering Chicago Quantum Exchange and Kadanoff Center for Theoretical Physics University of Chicago Illinois 60637 USA qBraid Co. Harper Court 5235 Chicago Illinois 60615 USA Department of Physics Harvard University Cambridge Massachusetts 02138 USA Department of Physics and Astronomy University of Iowa Iowa City Iowa 52242 USA Duke Quantum Center Duke University Durham North Carolina 27701 USA Department of Electrical and Computer Engineering Duke University Durham North Carolina 27708 USA Department of Physics Duke University

It is for the first time that quantum simulation for high-energy physics (HEP) is studied in the U.S. decadal particle-physics community planning, and in fact until recently, this was not considered a mainstream topic in the community. This fact speaks of a remarkable rate of growth of this subfield over the past few years, stimulated by the impressive advancements in quantum information sciences (QIS) and associated technologies over the past decade, and the significant investment in this area by the government and private sectors in the U.S. and other countries. High-energy physicists have quickly identified problems of importance to our understanding of nature at the most fundamental level, from tiniest distances to cosmological extents, that are intractable with classical computers but may benefit from quantum advantage. They have initiated, and continue to carry out, a vigorous program in theory, algorithm, and hardware co-design for simulations of relevance to the HEP mission. This Roadmap is an attempt to bring this exciting and yet challenging area of research to the spotlight, and to elaborate on what the promises, requirements, challenges, and potential solutions are over the next decade and beyond.

关键词： Quantum simulation

来源：评论

学校读者我要写书评

暂无评论

Constraints on the two-dimensional pseudospin-12 Mott insulator description of Sr2IrO4

引用

Physical Review B 2022年第24期105卷 245130-245130页

作者： B. Zwartsenberg R. P. Day E. Razzoli M. Michiardi M. X. Na G. Zhang J. D. Denlinger I. Vobornik C. Bigi B. J. Kim I. S. Elfimov E. Pavarini A. Damascelli Quantum Matter Institute University of British Columbia Vancouver Canada BC V6T 1Z4 Department of Physics and Astronomy University of British Columbia Vancouver Canada BC V6T 1Z1 Max Planck Institute for Chemical Physics of Solids Nöthnitzer Straße 40 01187 Dresden Germany Key Laboratory of Materials Physics Institute of Solid State Physics HFIPS Chinese Academy of Sciences Hefei 230031 People's Republic of China Advanced Light Source Lawrence Berkeley National Laboratory Berkeley California 94720 USA Istituto Officina dei Materiali (IOM)-CNR Laboratorio TASC in Area Science Park S.S.14 Km 163.5 I-34149 Trieste Italy Dipartimento di Fisica Universit di Milano Via Celoria 16 I-20133 Milano Italy Department of Physics Pohang University of Science and Technology Pohang 790-784 South Korea Center for Artificial Low Dimensional Electronic Systems Institute for Basic Science (IBS) 77 Cheongam-Ro Pohang 790-784 Republic of Korea Max Planck Institute for Solid State Research Heisenbergstraße 1 D-70569 Stuttgart Germany Institute for Advanced Simulation Forschungszentrum Jülich D-52425 Jülich Germany JARA High-Performance Computing Forschungszentrum Jülich D-52425 Jülich Germany

Sr2IrO4 has often been described via a simple, one-band pseudospin-12 model subject to electron-electron interactions on a square lattice, fostering analogies with cuprate superconductors believed to be well described by a similar model. In this work we argue—based on a detailed study of the low-energy electronic structure by circularly polarized spin and angle-resolved photoemission spectroscopy combined with dynamical mean-field theory calculations—that a pseudospin-12 model fails to capture the full complexity of the system. We show instead that a realistic multiband Hubbard Hamiltonian, accounting for the full correlated t2g manifold, provides a detailed description of the interplay between spin-orbital entanglement and electron-electron interactions and yields quantitative agreement with experiments. Our analysis establishes that the j3/2 states make up a substantial percentage of the low-energy spectral weight, i.e., approximately 74% as determined from the integration of the j-resolved spectral function in the 0 to −1.64eV energy range. The results in our work are of relevance not only to Ir-based materials but also more generally to multiorbital materials with closely spaced energy scales.

关键词： Spin-orbit coupling High-temperature superconductors Mott insulators Angle-resolved photoemission spectroscopy Dynamical mean field theory Hubbard model Spin-resolved photoemission spectroscopy

来源：评论

学校读者我要写书评

暂无评论

Constraints on the two-dimensional pseudo-spin 1/2 Mott insulator description of Sr2IrO4

arXiv

引用

arXiv 2022年

作者： Zwartsenberg, Berend Day, Ryan P. Razzoli, Elia Michiardi, Matteo Na, Meng Xing Zhang, Guoren Denlinger, Jonathan D. Vobornik, Ivana Bigi, Chiara Kim, Bum Joon Elfimov, Ilya S. Pavarini, Eva Damascelli, Andrea Quantum Matter Institute University of British Columbia VancouverBCV6T 1Z4 Canada Department of Physics and Astronomy University of British Columbia VancouverBCV6T 1Z1 Canada Max Planck Institute for Chemical Physics of Solids Nöthnitzer Straße 40 Dresden01187 Germany Key Laboratory of Materials Physics Institute of Solid State Physics Hfips Chinese Academy of Sciences Hefei230031 China Advanced Light Source Lawrence Berkeley National Laboratory BerkeleyCA94720 United States -CNR Laboratorio Tasc Area Science Park S.S.14 Km 163.5 TriesteI-34149 Italy Dipartimento di Fisica Universitá di Milano Via Celoria 16 MilanoI-20133 Italy Department of Physics Pohang University of Science and Technology Pohang790-784 Korea Republic of 77 Cheongam-Ro Pohang790-784 Korea Republic of Max Planck Institute for Solid State Research Heisenbergstraße 1 StuttgartD-70569 Germany Institute for Advanced Simulation Forschungszentrum Jülich JülichD-52425 Germany Jara High-Performance Computing Forschungszentrum Jülich Jülich Germany

Sr2IrO4has often been described via a simple, one-band pseudo-spin 1/2 model, subject to electron-electron interactions, on a square lattice, fostering analogies with cuprate superconductors, believed to be well described by a similar model. In this work we argue - based on a detailed study of the low-energy electronic structure by circularly polarized spin and angle-resolved photoemission spectroscopy combined with dynamical mean-field theory calculations - that a pseudo-spin 1/2 model fails to capture the full complexity of the system. We show instead that a realistic multi-band Hubbard Hamiltonian, accounting for the full correlated t2gmanifold, provides a detailed description of the interplay between spin-orbital entanglement and electron-electron interactions, and yields quantitative agreement with experiments. Our analysis establishes that the j3/2states make up a substantial percentage of the low energy spectral weight, i.e. approximately 74% as determined from the integration of the j-resolved spectral function in the 0 to -1.64 eV energy range. The results in our work are not only of relevance to iridium based materials, but more generally to the study of multi-orbital materials with closely spaced energy scales. © 2022, CC BY-NC-ND.

关键词： Electron-electron interactions

来源：评论

学校读者我要写书评

暂无评论

Tape-time processing: Kinetics and mechanisms of native oxidation of transition metal dichalcogenides ZrSxSe2-x and MoS2

arXiv

引用

arXiv 2020年

作者： Jo, Seong Soon Singh, Akshay Yang, Liqiu Tiwari, Subodh C. Hong, Sungwook Krishnamoorthy, Aravind Sales, Maria Gabriela Oliver, Sean M. Fox, Joshua Cavalero, Randal L. Snyder, David W. Vora, Patrick M. McDonnell, Stephen J. Vashishta, Priya Kalia, Rajiv K. Nakano, Aiichiro Jaramillo, Rafael Department of Materials Science and Engineering Massachusetts Institute of Technology CambridgeMA02139 United States Collaboratory for Advanced Computing and Simulation University of Southern California Los AngelesCA90089 United States Department of Physics and Engineering California State University BakersfieldCA93311 United States Department of Materials Science and Engineering University of Virginia CharlottesvilleVA22904 United States Electronic Materials and Devices Department Applied Research Laboratory and 2-Dimensional Crystal Consortium Materials Research Institute Pennsylvania State University University ParkPA16802 United States Department of Physics and Astronomy George Mason University FairfaxVA22030 United States Quantum Materials Center George Mason University FairfaxVA22030 United States

A thorough understanding of the processing and properties of native oxides is essential for designing semiconductor devices. This is no less true for nanomaterials than it is for legacy semiconductors such as silicon, for which control and understanding of the native oxide was a seminal achievement of 20th century materials science. Layered transition metal dichalcogenides nominally have inert, fully-passivated surfaces, but it is well-known that this is an oversimplification and that many TMDs oxidize readily. Here we report on experiments and simulations that reveal the rate and mechanism of oxidation of MoS2 and ZrSxSe2-x alloys in laboratory conditions. We find that MoS2 surfaces are indeed stable, with no oxidation for up to a year exposure. In contrast, ZrSxSe2-x alloys oxidize spontaneously and the oxide growth is not self-limited. Oxidation proceeds by Zr-O bond switching that collapses the van der Waals gaps, and is facilitated by progressive redox transitions of the chalcogen. In contrast, the MoS2 surface remains inert due to energetically-unfavorable oxygen adsorption. Our results provide quantitative and conceptual guidance for designing and processing semiconductor devices based on MoS2 and ZrSxSe2-x, and identify the atomistic-scale mechanisms of bonding and phase transformations in layered materials with competing anions. Copyright © 2020, The Authors. All rights reserved.

关键词： Transition metals

来源：评论

学校读者我要写书评

暂无评论

Exciton behavior under the influence of metal nanoparticle near fields: Significance of nonlocal effects

引用

Physical Review B 2018年第11期98卷 115430-115430页

作者： Harini Hapuarachchi Sarath D. Gunapala Qiaoliang Bao Mark I. Stockman Malin Premaratne Advanced Computing and Simulation Laboratory (AχL) Department of Electrical and Computer Systems Engineering Monash University Clayton Victoria 3800 Australia Jet Propulsion Laboratory California Institute of Technology Pasadena California 91109 USA Department of Materials Science and Engineering Monash University Clayton Victoria 3800 Australia Department of Physics and Astronomy Georgia State University Atlanta Georgia 30303 USA

We analytically characterize the influence of a neighboring metal nanoparticle (MNP) on the behavioral trends of a quantum dot (QD) using a generalized nonlocal optical response (GNOR) method based approach, taking the MNP distance dependent modifications to the QD population relaxation and dephasing rates into account. The GNOR model is a recent generalization and an extension of the hydrodynamic Drude model (HDM), which goes beyond HDM by taking into account both the convection current and electron diffusion in the MNPs. It allows unified theoretical explanation of some experimentally observed plasmonic phenomena which otherwise would require ab initio analysis as the conventional local response approximation (LRA) fails to account for them. For example, it has been demonstrated in literature that the GNOR model captures size dependent resonance shifts of small MNPs which are unrevealed by the conventional LRA based methods, and it has proven to yield results displaying better agreement with the experimental observations for plasmonic experiments. Attempts to incorporate MNP nonlocal effects in the analytical characterization of vicinal excitons found in literature utilize the phenomenological hydrodynamic model and assume the absence of MNP interband effects. Moreover, they are only applicable to narrow parameter regions. In this paper we present a complete analytical characterization which overcomes these drawbacks and lends to the perusal of the system over wide continua of various parameters, enabling us to get an elevated view at a much lesser level of complexity compared to the conventional LRA based numerical methods or the conventional ab initio methods of accounting for the nonlocal effects. Our proposed GNOR based model predicts strong modifications to various QD properties such as population difference, absorption, MNP induced shifts to excitonic energy and Förster enhanced broadening, coherent plasmonic field enhancement, and quantum state purity, comp

关键词： Excitons Near-field optics Plasmonics Nanoparticles Quantum dots

来源：评论

学校读者我要写书评

暂无评论

26th Annual Computational Neuroscience Meeting (CNS*2017): Part 3 Antwerp, Belgium. 15-20 July 2017 Abstracts

引用

BMC NEUROSCIENCE 2017年第SUPPL 1期18卷 95-176页

作者： [Anonymous] Department of Neuroscience Yale University New Haven CT 06520 USA Department Physiology & Pharmacology SUNY Downstate Brooklyn NY 11203 USA NYU School of Engineering 6 MetroTech Center Brooklyn NY 11201 USA Departament de Matemàtica Aplicada Universitat Politècnica de Catalunya Barcelona 08028 Spain Institut de Neurobiologie de la Méditerrannée (INMED) INSERM UMR901 Aix-Marseille Univ Marseille France Center of Neural Science New York University New York NY USA Aix-Marseille Univ INSERM INS Inst Neurosci Syst Marseille France Laboratoire de Physique Théorique et Modélisation CNRS UMR 8089 Université de Cergy-Pontoise 95300 Cergy-Pontoise Cedex France Department of Mathematics and Computer Science ENSAT Abdelmalek Essaadi’s University Tangier Morocco Laboratory of Natural Computation Department of Information and Electrical Engineering and Applied Mathematics University of Salerno 84084 Fisciano SA Italy Department of Medicine University of Salerno 84083 Lancusi SA Italy Dipartimento di Fisica Università degli Studi Aldo Moro Bari and INFN Sezione Di Bari Italy Data Analysis Department Ghent University Ghent Belgium Coma Science Group University of Liège Liège Belgium Cruces Hospital and Ikerbasque Research Center Bilbao Spain BIOtech Department of Industrial Engineering University of Trento and IRCS-PAT FBK 38010 Trento Italy Department of Data Analysis Ghent University Ghent 9000 Belgium The Wellcome Trust Centre for Neuroimaging University College London London WC1N 3BG UK Department of Electronic Engineering NED University of Engineering and Technology Karachi Pakistan Blue Brain Project École Polytechnique Fédérale de Lausanne Lausanne Switzerland Departement of Mathematics Swansea University Swansea Wales UK Laboratory for Topology and Neuroscience at the Brain Mind Institute École polytechnique fédérale de Lausanne Lausanne Switzerland Institute of Mathematics University of Aberdeen Aberdeen Scotland UK Department of Integrativ

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：