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Dynamical amplification of electric polarization through nonlinear phononics in 2D SnTe

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npj Computational Materials 2020年第1期6卷 155-162页

作者： Dongbin Shin Shunsuke A.Sato hannes hübener Umberto De Giovannini Noejung Park Angel Rubio Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science Luruper Chaussee 149Hamburg 22761Germany Center for Computational Sciences University of TsukubaTsukuba 305-8577Japan Nano-Bio Spectroscopy Group Departamento de Fisica de MaterialesUniversidad del Pas VascoSan Sebastian 20018Spain Department of Physics Ulsan National Institute of Science and TechnologyUNIST-gil 50Ulsan 44919Korea Center for Computational Quantum Physics(CCQ) The Flatiron Institute162 Fifth AvenueNew YorkNY 10010USA

Ultrafast optical control of ferroelectricity using intense terahertz fields has attracted significant *** we show that the nonlinear interactions between two optical phonons in SnTe,a two-dimensional in-plane ferroelectric material,enables a dynamical amplification of the electric polarization within subpicoseconds time *** first-principles time-dependent simulations show that the infrared-active out-of-plane phonon mode,pumped to nonlinear regimes,spontaneously generates in-plane motions,leading to rectified oscillations in the in-plane electric *** suggest that this dynamical control of ferroelectric material,by nonlinear phonon excitation,can be utilized to achieve ultrafast control of the photovoltaic or other nonlinear optical responses.

关键词： nonlinear ferroelectric phonon

Common microscopic origin of the phase transitions in Ta_(2)NiS_(5) and the excitonic insulator candidate Ta_(2)NiSe_(5)

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npj Computational Materials 2021年第1期7卷 1919-1932页

作者： Lukas Windgätter Malte Rösner Giacomo Mazza hannes hübener Antoine Georges Andrew J.Millis Simone Latini Angel Rubio Max Planck Institute for the Structure and Dynamics of Matter Luruper Chaussee 14922761 HamburgGemany Radboud University Institute for Molecules and MaterialsHeijendaalseweg 1356525 AJ NijmegenNetherlands Department of Quantum Matter Physics University of GenevaQuai Ernest-Ansermet 241211 GenevaSwitzerland College de France 11 place Marcelin Berthelot75005 ParisFrance Center for Computational Quantum Physics Flatiron InstituteNew YorkNY 10010USA.CPHTCNRSEcole PolytechniqueIP Paris91128 PalaiseauFrance Department of Physics Columbia UniversityNew YorkNY 10027USA.Nano-Bio Spectroscopy Group Departamento de Fisica de Materiales Universidad del Pais Vasco20018 San SebastianSpain

The structural phase transition in Ta-NiSes has been envisioned as driven by the formation of an excitonic insulating ***,the role of structural and electronic instabilities on crystal symmetry breaking has yet to be ***,the phase transition in its complementary material Ta_(2)NiS_(5)does not show any experimental hints of an excitonic insulating *** present a microscopic investigation of the electronic and phononic effects involved in the structural phase transition in Ta_(2)NiSe_(5)and Ta-Niss using extensive first-principles *** both materials the crystal symmetries are broken by phonon instabilities,which in tum lead to changes in the electronic bandstructure also observed in the experiment.A total energy landscape analysis shows no tendency towards a purely electronic instability and we find that a sizeable lattice distortion is needed to open a *** conclude that an excitonic instability is not needed to explain the phase transition in both Ta_(2)NiSe_(5)and Ta_(2)NiS_(5).

关键词： phase structural transitions

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进行中的弗洛凯能带工程

Science Bulletin 2023年第8期68卷 751-752页

作者： hannes hübener Umberto De Giovannini Shunsuke A.Sato Angel Rubio Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science Hamburg 22761Germany Universitàdegli Studi di Palermo Dipartimento di Fisica e Chimica—Emilio SegrèPalermo I-90123Italy Center for Computational Sciences University of TsukubaTsukuba 305-8577Japan Center for Computational Quantum Physics(CCQ) The Flatiron InstituteNew York NY 10010USA

In a recent article in Nature,Zhou et al.[1]reported an impressive demonstration of Floquet materials *** this field researchers aim at creating properties in materials that they do not usually exhibit in their equilibrium *** scope ranges from inducing phase transitions in out-of-equilibrium that can otherwise only be achieved by pressure or doping.

关键词：能带工程 equilibrium otherwise

Automatic object annotation in streamed and remotely explored large 3D reconstructions

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Computational Visual Media 2021年第1期7卷 71-86页

作者： Benjamin holler Annette Mossel hannes Kaufmann Institute of Visual Computing and human-Centered Technology Vienna University of TechnologyFavoritenstraβe 9-11/193/06A-1040 ViennaAustria

We introduce a novel framework for 3 D scene reconstruction with simultaneous object annotation,using a pre-trained 2 D convolutional neural network(CNN),incremental data streaming,and remote exploration,with a virtual reality *** enables versatile integration of any 2 D box detection or segmentation *** integrate new approaches to(i)asynchronously perform dense 3 D-reconstruction and object annotation at interactive frame rates,(ii)efficiently optimize CNN results in terms of object prediction and spatial accuracy,and(iii)generate computationally-efficient colliders in large triangulated3 D-reconstructions at run-time for 3 D scene *** method is novel in combining CNNs with long and varying inference time with live 3 D-reconstruction from RGB-D camera *** further propose a lightweight data structure to store the 3 D-reconstruction data and object annotations to enable fast incremental data transmission for real-time exploration with a remote client,which has not been presented *** framework achieves update rates of 22 fps(SSD Mobile Net)and 19 fps(Mask RCNN)for indoor environments up to 800 m^(3).We evaluated the accuracy of 3 D-object *** work provides a versatile foundation for semantic scene understanding of large streamed3 D-reconstructions,while being independent from the CNN’s processing *** code is available for non-commercial use.

关键词： dense 3D reconstruction object detection CNN distributed virtual reality

Petrology,geochronology,and geophysical characterization of Mesoproterozoic rocks in central Illinois,USA

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Geoscience Frontiers 2020年第2期11卷 581-596页

作者： Jared T.Freiburg John hMcBride David hMalone hannes ELeetaru Illinois State Geological Survey Prairie Research InstituteUniversity of Illinois at Urbana-Champaign615 E.Peabody DriveChampaignIL 61820USA University of Greifswald Institute of Geography and GeologyFriedrich-Ludwig-Jahn Str.17aD-17489 GreifswaldGermany Department of Geological Sciences Brigham Young UniversityProvoUT84602USA Department of Geography Geologyand the EnvironmentCampus Box 4400Illinois State UniversityNormalIL61790-4400USA

The Precambrian basement rocks of the Eastern Granite-Rhyolite Province(EGRP)in central Illinois(midcontinent region of North America)exhibit a complex history of early volcanism,granite emplacement,and intrusion of mafic rocks.A comprehensive suite of dedicated petrographic analyses,geophysical logs,and drill core from four basement-penetrating wells,two-dimensional and three-dimensional seismic reflection data,and U-Pb age data from the Illinois Basin–Decatur Project(IBDP)and Illinois Carbon Capture Storage(ICCS)Project site provide new constraints for interpreting the Precambrian basement of the Illinois *** new data reveal the basement to be compositionally and structurally complex,having typical EGRP felsic volcanic rocks intruded by the first reported gabbro in the Precambrian basement in ***(n?29)from rhyolite give a U-Pb weighted mean average age of 14679 ***(n?3)from a gabbro dike that intrudes the rhyolite yield a concordia age of 107312 Ma,which corresponds to Grenville-age extension and represents the first Grenville-age rock in Illinois and in the EGRP.A high-resolution three-dimensional seismic reflection volume,coincident with the four wells,provides a context for interpreting the petrological data and implies a high degree of heterogeneity for basement rocks at the IBDP–ICCS site,as also shown by the drill *** occurrence of Grenville-age gabbro is related to a prominent bowl-like structure observed on local two-dimensional seismic reflection profiles and the three-dimensional volume that is interpreted as a deep-seated mafic sill ***,heterogeneities such as the brecciated EGRP rhyolite and later gabbro intrusion observed in the basement lithology at the IBDP–ICCS may reflect previously unknown distal elements of the 1.1 Ga Midcontinent Rift in the EGRP and more likely Grenville-age extension.

关键词： Eastern granite-rhyolite province Mesoproterozoic Carbon storage Reflection seismology Zircon U-Pb geochronology Illinois

The role of GI-supported methods in crisis management

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International Journal of Digital Earth 2010年第4期3卷 340-354页

作者： hannes Seppänen Kirsi Virrantaus Department of Surveying Aalto University School of Science and TechnologyP.O.Box 11200Aalto 00076Finland

Crisis and disaster management has become an important research field in GIS during recent *** assessment and situation picture-related work are particularly important areas of *** are distinct phases in different crises;these can be roughly divided into mitigation,preparedness,response,and *** this paper a general classification of methods in each phase is given with examples on recent or ongoing research *** framework is based on literature and experiences from crisis and disaster-related *** case studies are based on those *** goal is to clarify the role and usability of various GI-supported methods in the crisis management process by outlining a theoretical framework and presenting examples of the developed *** increasing amount of spatially related geographic information is a huge potential to the GI analysis and modeling methods;the concept of digital earth is the underlying mainstream that gives lots of promise to the research and development work in this field.

关键词： geo-spatial science geoinformatics GIS digital earth crisis management

Vulnerability and Resilience Research:A Critical Perspective

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International Journal of Disaster Risk Science 2014年第1期5卷 86-87页

作者： hannes Taubenbock Christian Geiв German Remote Sensing Data Center German Aerospace CenterOberpfaffenhofen82234 WesslingGermany

‘‘Vulnerability’’and‘‘resilience’’are terms of such broad conceptual meaning as to be almost useless for careful scientific communication,except as rhetorical indicators of areas of greatest *** is a reflection of the complexity of their meaning,an uncoordinated search among different fields for a common understanding,and maybe the difficulty of systematizing these complicated issues among the various involved parties.

关键词： Resilience difficulty coordinated

Statistics for Surface Modes of Nanoparticles with Shape Fluctuations

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Communications in Computational Physics 2010年第10期8卷 1224-1241页

作者： Felix Ruting hannes Uecker Institut fur Physik Carl von Ossietzky UniversitatOldenburg D-26111Germany Institut fur Mathematik Carl von Ossietzky UniversitatOldenburg D-26111Germany

We develop a numerical method for approximating the surface modes of sphere-like nanoparticles in the quasi-static limit,based on an expansion of(the angular part of)the potentials into spherical *** of the results obtained in this manner with exact solutions and with a perturbation ansatz prove that the scheme is accurate if the shape deviations from a sphere are not too *** method allows fast calculations for large numbers of particles,and thus to obtain statistics for nanoparticles with random shape *** an application we present some statistics for the distribution of resonances,polariziabilities,and dipole axes for particles with random perturbations.

关键词： Electrostatic(boundary-value problems) collective excitations(plasmons) shape fluctuations numerical scheme spherical harmonics projection method

Global geospatial data from Earth observation:status and issues

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International Journal of Digital Earth 2017年第4期10卷 328-341页

作者： Ian Dowman hannes I.Reuter Department of Civil Environmental and Geomatic EngineeringUniversity College LondonLondonUK Gisexperts TrierGermany

Data covering the whole of the surface of the Earth in a homogeneous and reliable manner has been accumulating over many *** type of data became available from meteorological satellites from the 1960s and from Earth-observing satellites at a small scale from the early 1970s but has gradually accumulated at larger scales up to the present day when we now have data covering many environmental themes at large *** data have been used to generate information which is presented in the form of global data *** paper will give a brief introduction to the development of Earth observation and to the organisations and sensors which collect data and produce global geospatial data *** of accessing global data sets will set out the types of data available that will be *** elevation models are discussed in a separate section because of their importance in georeferencing image data as well as their application to analysis of thematic *** paper will also examine issues of availability,accuracy,validation and reliability and will look at future challenges.

关键词： Global data sets validation standardisation Earth observation