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arXiv 2023年

作者： Yang, Liqiu Jaramillo, Rafael Kalia, Rajiv K. Nakano, Aiichiro Vashishta, Priya Collaboratory for Advanced Computing and Simulation University of Southern California Los AngelesCA90089-0242 United States Department of Materials Science and Engineering Massachusetts Institute of Technology CambridgeMA02139 United States

Understanding oxidation mechanisms of layered semiconducting transition-metal dichalcogenide (TMDC) is important not only for controlling native oxide formation but also for synthesis of oxide and oxysulfide products. Here, reactive molecular dynamics simulations show that oxygen partial pressure controls not only the ZrS2 oxidation rate but also the oxide morphology and quality. We find a transition from layer-by-layer oxidation to amorphous-oxide-mediated continuous oxidation as the oxidation progresses, where different pressures selectively expose different oxidation stages within a given time window. While the kinetics of the fast continuous oxidation stage is well described by the conventional Deal-Grove model, the layer-by-layer oxidation stage is dictated by reactive bond-switching mechanisms. This work provides atomistic details and a potential foundation for rational pressure-controlled oxidation of broad TMDC materials. Copyright © 2023, The Authors. All rights reserved.

关键词： Molecular dynamics

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

arXiv

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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

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Shock-Induced Decomposition of 1, 3, 5-triamino-2, 4, 6-trinitrobenzene: A Reactive-Force-Field Molecular Dynamics Study

Shock-Induced Decomposition of 1, 3, 5-triamino-2, 4, 6-trin...

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作者： Tiwari, Subodh C. Nomura, Ken-Ichi Kalia, Rajiv Nakano, Aiichiro Vashishta, Priya Collaboratory for Advanced Computing and Simulation Department of Chemical Engineering and Materials Science University of Southern California Los AngelesCA90089-0242 United States Department of Physics and Astronomy Department of Computer Science University of Southern California Los AngelesCA90089-0242 United States

Shock-induced detonation simulation provides critical information about high explosive (HE) materials including sensitivity, detonation velocity and reaction pathways. Here, we report a reactive force-field molecular dynamics simulation study of shock-induced decomposition of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) crystal. A flyer acts as mechanical stimuli to induce shock in the system, which initiates chemical reactions. Reaction pathway study reveals that the detonation process of TATB is distinct from those in Octahydro-1,3,5,7-tetranitro-1,3,4,7-terazocine (HMX) and 1,3,5-Trinitro-1,3,5-triazacyclohexane (RDX). Unlike the latter HE materials, N2 production in TATB occurs via three different intermolecular reaction pathways. Being an oxygen deficient HE material, a large carbon rich aggregate remains after the reaction. Copyright © Materials Research Society 2016.

关键词： Detonation

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Author Correction: Why rankings of biomedical image analysis competitions should be interpreted with care

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Nature communications 2019年第1期10卷 588页

作者： Lena Maier-Hein Matthias Eisenmann Annika Reinke Sinan Onogur Marko Stankovic Patrick Scholz Tal Arbel Hrvoje Bogunovic Andrew P Bradley Aaron Carass Carolin Feldmann Alejandro F Frangi Peter M Full Bram van Ginneken Allan Hanbury Katrin Honauer Michal Kozubek Bennett A Landman Keno März Oskar Maier Klaus Maier-Hein Bjoern H Menze Henning Müller Peter F Neher Wiro Niessen Nasir Rajpoot Gregory C Sharp Korsuk Sirinukunwattana Stefanie Speidel Christian Stock Danail Stoyanov Abdel Aziz Taha Fons van der Sommen Ching-Wei Wang Marc-André Weber Guoyan Zheng Pierre Jannin Annette Kopp-Schneider Division of Computer Assisted Medical Interventions (CAMI) German Cancer Research Center (DKFZ) 69120 Heidelberg Germany. l.maier-hein@dkfz.de. Division of Computer Assisted Medical Interventions (CAMI) German Cancer Research Center (DKFZ) 69120 Heidelberg Germany. Centre for Intelligent Machines McGill University Montreal QC H3A0G4 Canada. Christian Doppler Laboratory for Ophthalmic Image Analysis Department of Ophthalmology Medical University Vienna 1090 Vienna Austria. Science and Engineering Faculty Queensland University of Technology Brisbane QLD 4001 Australia. Department of Electrical and Computer Engineering Department of Computer Science Johns Hopkins University Baltimore MD 21218 USA. CISTIB - Center for Computational Imaging & Simulation Technologies in Biomedicine The University of Leeds Leeds Yorkshire LS2 9JT UK. Department of Radiology and Nuclear Medicine Medical Image Analysis Radboud University Center 6525 GA Nijmegen The Netherlands. Institute of Information Systems Engineering TU Wien 1040 Vienna Austria. Complexity Science Hub Vienna 1080 Vienna Austria. Heidelberg Collaboratory for Image Processing (HCI Heidelberg University 69120 Heidelberg Germany. Centre for Biomedical Image Analysis Masaryk University 60200 Brno Czech Republic. Electrical Engineering Vanderbilt University Nashville TN 37235-1679 USA. Institute of Medical Informatics Universität zu Lübeck 23562 Lübeck Germany. Division of Medical Image Computing (MIC) German Cancer Research Center (DKFZ) 69120 Heidelberg Germany. Institute for Advanced Studies Department of Informatics Technical University of Munich 80333 Munich Germany. Information System Institute HES-SO Sierre 3960 Switzerland. Departments of Radiology Nuclear Medicine and Medical Informatics Erasmus MC 3015 GD Rotterdam The Netherlands. Department of Computer Science University of Warwick Coventry CV4 7AL UK. Department of Radiation Oncology Massachusetts General Hospital Boston MA

In the original version of this Article the values in the rightmost column of Table 1 were inadvertently shifted relative to the other columns. This has now been corrected in the PDF and HTML versions of the Article.

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De novo ultrascale atomistic simulations on high-end parallel supercomputers

De novo ultrascale atomistic simulations on high-end paralle...

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作者： Nakano, Aiichiro Kalia, Rajiv K. Nomura, Ken-Ichi Sharma, Ashish Vashishta, Priya Shimojo, Fuyuki van Duin, Adri C.T. Goddard III, William Biswas, Rupak Srivastava, Deepak Yang, Lin H. Collaboratory for Advanced Computing and Simulations University of Southern California Los Angeles CA 90089-0242 United States Department of Biomedical Informatics Ohio State University Columbus OH 43210 United States Department of Physics Kumamoto University Kumamoto 860-8555 Japan Materials and Process Simulation Center California Institute of Technology Pasadena CA 91125 United States Division NASA Amesresearch Center Moffett Field CA 94035 United States Physics/HDivision Lawrence Livermore National Laboratory Livermore CA 94551 United States

We present a de novo hierarchical simulation framework for first-principles based predictive simulations of materials and their validation on high-end parallel supercomputers and geographically distributed clusters. In this framework, high-end chemically reactive and non-reactive molecular dynamics (MD) simulations explore a wide solution space to discover microscopic mechanisms that govern macroscopic material properties, into which highly accurate quantum mechanical (QM) simulations are embedded to validate the discovered mechanisms and quantify the uncertainty of the solution. The framework includes an embedded divide-and-conquer (EDC) algorithmic framework for the design of linear-scaling simulation algorithms with minimal bandwidth complexity and tight error control. The EDC framework also enables adaptive hierarchical simulation with automated model transitioning assisted by graph-based event tracking. A tunable hierarchical cellular decomposition parallelization framework then maps the O(N) EDC algorithms onto petaflops computers, while achieving performance tunability through a hierarchy of parameterized cell data/ computation structures, as well as its implementation using hybrid grid remote procedure call + message passing + threads programming. High-end computing platforms such as IBM BlueGene/L, SGI Altix 3000 and the NSF TeraGrid provide an excellent test grounds for the framework. On these platforms, we have achieved unprecedented scales of quantum-mechanically accurate and well validated, chemically reactive atomistic simulations-1.06 billion-atom fast reactive force-field MD and 11.8 million-atom (1.04 trillion grid points) quantum-mechanical MD in the framework of the EDC density functional theory on adaptive multigrids- in addition to 134 billion-atom non-reactive space-time multiresolution MD, with the parallel efficiency as high as 0.998 on 65,536 dual-processor BlueGene/L nodes. We have also achieved an automated execution of hierarchical QM/MD

关键词： Supercomputers

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