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Machine learning for exploring small polaron configurational space

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npj computational Materials 2022年第1期8卷 1183-1191页

作者： Viktor c.Birschitzky Florian Ellinger Ulrike Diebold michele Reticcioli cesare Franchini University of Vienna Faculty of Physics and Center for Computational Materials ScienceViennaAustria University of Vienna Vienna Doctoral School in PhysicsBoltzmanngasse 51090ViennaAustria Institute of Applied Physics Technische Universität Wien1040ViennaAustria Department of Physics and Astronomy’Augusto Righi’ Alma Mater Studiorum-Universitàdi BolognaBologna40127Italy

Polaron defects are ubiquitous in materials and play an important role in many processes involving carrier mobility,charge transfer and surface *** small polarons’spatial distributions is essential to understand materials properties and ***,the required exploration of the configurational space is computationally demanding when using first principles ***,we propose a machine-learning(ML)accelerated search that determines the ground state polaronic *** ML model is trained on databases of polaron configurations generated by density functional theory(DFT)via molecular dynamics or random *** establish a mapping between configurations and their stability,we designed descriptors modelling the interactions among polarons and charged point *** used the DFT+ML protocol to explore the polaron configurational space for two surface-systems,reduced rutile TiO_(2)(110)and Nb-doped SrTiO_(3)(001).The ML-aided search proposes additional polaronic configurations and can be utilized to determine optimal polaron distributions at any charge concentration.

关键词： configuration polaron charge

Hot electrons in water: injection and ponderomotive acceleration by means of plasmonic nanoelectrodes

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Light(Science & Applications) 2017年第1期6卷 744-751页

作者： Pierfrancesco Zilio michele Dipalo Francesco Tantussi Gabriele c Messina Francesco de Angelis Istituto Italiano di Tecnologia 16163GenovaItaly

We present a theoretical and experimental study of a plasmonic nanoelectrode architecture that is able to inject bunches of hot electrons into an aqueous *** this approach,electrons are accelerated in water by ponderomotive forces up to energies capable of exciting or ionizing water *** ability is enabled by the nanoelectrode structure(extruding out of a metal baseplate),which allows for the production of an intense plasmonic hot spot at the apex of the structure while maintaining the electrical connection to a virtually unlimited charge *** electron injection is experimentally monitored by recording the current transmitted through the water medium,whereas the electron acceleration is confirmed by observation of the bubble generation for a laser power exceeding a proper *** understanding of the complex physics involved is obtained via a numerical approach that explicitly models the electromagnetic hot spot generation,electron-by-electron injection via multiphoton absorption,acceleration by ponderomotive forces and electron-water interaction through random elastic and inelastic *** model predicts a critical electron density for bubble nucleation that nicely matches the experimental findings and reveals that the efficiency of energy transfer from the plasmonic hot spot to the free electron cloud is much more efficient(17 times higher)in water than in a *** of their high kinetic energy and large reduction potential,these proposed wet hot electrons may provide new opportunities in photocatalysis,electrochemical processes and hot-electron driven chemistry.

关键词： hot electrons hydrated electrons lightwave electronics plasmonics ponderomotive acceleration strong-field photoemission water breakdown

Recycled Aggregates:Production,Properties and Value-added Sustainable Applications

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Journal of Wuhan University of Technology(Materials Science) 2010年第6期25卷 1011-1016页

作者： LIMBAcHIYA M c School of civil Engineering & construction Faculty of EngineeringKingston University-London KT1 2EEUK

Part of an extensive research undertaken by the concrete and Masonry Research Group at kingston University-London was reported to demonstrate through scientific research and full-scale site trials,that quality recycled concrete aggregates can be produced and can be used successfully in a range of concrete *** effects of up to 100% coarse recycled concrete aggregate（RcA） on fresh,engineering and durability related properties were established and assessed its suitability for use in a rage of sustainable applications.

关键词： construction and demolition waste recycling recycled concrete aggregate fresh properties engineering and durability performance

Thermodynamics and dielectric response of BaTiO_(3)by data-driven modeling

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npj computational Materials 2022年第1期8卷 1998-2014页

作者： Lorenzo Gigli Max Veit michele Kotiuga Giovanni Pizzi Nicola Marzari michele ceriotti Laboratory of computational Science and Modeling(cOSMO) Institute of MaterialsÉcole Polytechnique Fédérale de LausanneCH-1015LausanneSwitzerland Theory and Simulation of Materials(THEOS)and National centre for computational Design and Discovery of Novel Materials(MARVEL) École Polytechnique Fédérale de LausanneCH-1015LausanneSwitzerland

Modeling ferroelectric materials from first principles is one of the successes of density-functional theory and the driver of much development effort,requiring an accurate description of the electronic processes and the thermodynamic equilibrium that drive the spontaneous symmetry breaking and the emergence of macroscopic *** demonstrate the development and application of an integrated machine learning model that describes on the same footing structural,energetic,and functional properties of barium titanate(BaTiO_(3)),a prototypical *** model uses ab initio calculations as a reference and achieves accurate yet inexpensive predictions of energy and polarization on time and length scales that are not accessible to direct ab initio *** predictions allow us to assess the microscopic mechanism of the ferroelectric *** presence of an order-disorder transition for the Ti off-centered states is the main driver of the ferroelectric transition,even though the coupling between symmetry breaking and cell distortions determines the presence of intermediate,partly-ordered ***,we thoroughly probe the static and dynamical behavior of BaTiO_(3)across its phase diagram without the need to introduce a coarse-grained description of the ferroelectric ***,we apply the polarization model to calculate the dielectric response properties of the material in a full ab initio manner,again reproducing the correct qualitative experimental behavior.

关键词： transition ferroelectric dielectric

Influence of railway wheel tread damage on wheel-rail impact loads and the durability of wheelsets

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Railway Engineering Science 2024年第1期32卷 20-35页

作者： michele Maglio Tore Vernersson Jens c.O.Nielsen Anders Ekberg Elena Kabo cHARMEc Department of Mechanical and Maritime SciencesChalmers University of TechnologySE‑41296 GothenburgSweden

Dynamic wheel-rail contact forces induced by a severe form of wheel tread damage have been measured by a wheel impact load detector during full-scale field tests at different vehicle *** on laser scanning,the measured three-dimensional damage geometry is employed in simulations of dynamic vehicle-track interaction to calibrate and verify a simulation *** relation between the magnitude of the impact load and various operational parameters,such as vehicle speed,lateral position of wheel-rail contact,track stiffness and position of impact within a sleeper bay,is *** calibrated model is later employed in simulations featuring other forms of tread damage;their effects on impact load and subsequent fatigue impact on bearings,wheel webs and subsurface initiated rolling contact fatigue of the wheel tread are *** results quantify the effects of wheel tread defects and are valuable in a shift towards condition-based maintenance of running gear,and for general assessment of the severity of different types of railway wheel tread damage.

关键词： Wheel tread damage Rolling contact fatigue cluster Field measurements Dynamic vehicle-track interaction Wheel-rail impact load Wheelset durability

Tight-binding models for ultracold atoms in optical lattices：general formulation and applications

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Science china(Physics,Mechanics & Astronomy) 2016年第6期59卷 1-23页

作者： michele Modugno Julen Ibanez-Azpiroz Giulio Pettini Departamento de Fisica Teorica e Historia de la ciencia Universidad del Pais Vasco UPV/EHU Bilbao 48080 Spain IKERBASQUE Basque Foundation for Science Bilbao 48011 Spain Peter Griinberg Institute and Institute for Advanced Simulation Forschungszentrum Jiilich & JARA Jiilich D-52425 Germany Dipartimento di Fisica e Astronomia Universita di Firenze and INFN Sesto Fiorentino 50019 Italy

Tight-binding models for ultracold atoms in optical lattices can be properly defined by using the concept of maximally localized Wannier functions for composite bands. The basic principles of this approach are reviewed here, along with different applications to lattice potentials with two minima per unit cell, in one and two spatial dimensions. Two independent methods for computing the tight-binding coefficients—one ab initio, based on the maximally localized Wannier functions, the other through analytic expressions in terms of the energy spectrum—are considered. In the one dimensional case, where the tight-binding coefficients can be obtained by designing a specific gauge transformation, we consider both the case of quasi resonance between the two lowest bands, and that between s and p orbitals. In the latter case, the role of the Wannier functions in the derivation of an effective Dirac equation is also reviewed. Then, we consider the case of a two dimensional honeycomb potential, with particular emphasis on the Haldane model, its phase diagram, and the breakdown of the Peierls substitution. Tunable honeycomb lattices, characterized by movable Dirac points, are also considered. Finally, general considerations for dealing with the interaction terms are presented.

关键词： ultracold atoms optical lattices tight-binding models Wannier functions effective Dirac equation honeycomb lattices

Quantum symmetrization transition in superconducting sulfur hydride from quantum Monte carlo and path integral molecular dynamics

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npj computational Materials 2024年第1期10卷 2657-2668页

作者： Romain Taureau Marco cherubini Tommaso Morresi michele casula Institut de Minéralogie de Physique des Matériaux et de CosmochimieSorbonne UniversitéCNRS UMR 7590MNHN4 Place Jussieu75252 ParisFrance European center for Theoretical Studies in Nuclear Physics and Related Areas—Fondazione Bruno Kessler* 286 Strada delle Tabarelle38123 TrentoItaly

We study the structural phase transition,originally associated with the highest superconducting critical temperature T_(c) measured in high-pressure sulfur hydride.A quantitative description of its pressure dependence has been elusive for any ab initio theory attempted so far,raising questions on the actual mechanism leading to the maximum of T_(c).Here,we estimate the critical pressure of the hydrogen bond symmetrization in the Im3m structure,by combining density functional theory and quantum Monte carlo simulations for electrons with path integral molecular dynamics for quantum nuclei.

关键词： quantum hydride sulfur

Tail risks and infectious disease: Influenza mortality in the U.S., 1900-2018

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Infectious Disease Modelling 2021年第1期6卷 1135-1143页

作者： michele campolieti Department of Management University of Toronto Scarborough1095 Military TrailTorontoOntarioM1C 1A4Canada

I use extreme values theory and data on influenza mortality from the *** 1900 to 2018 to estimate the tail risks of mortality.I find that the distribution for influenza mortality rates is heavy-tailed,which suggests that the tails of the mortality distribution are more informative than the events of high frequency(i.e.,years of low mortality).I also discuss the implications of my estimates for risk management and pandemic planning.

关键词： Influenza mortality rates Extremes value theory Generalized Pareto distribution Heavy-tails Tail risks

Physical and chemical processes promoting dominance of the toxic cyanobacterium cylindrospermopsis raciborskii

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chinese Journal of Oceanology and Limnology 2011年第4期29卷 883-891页

作者： michele A. BURFORD Timothy W. DAVIS Australian Rivers Institute Griffith University Nathan Qld. 4111 Australia

The freshwater cyanobacterium, cylindrospermopsis raciborskii （Woloszyflska） Seenayya and Subba Raju is a common species in lakes and reservoirs globally. In some areas of the world it can produce cytoand hepatotoxins （cylindrospermopsins, saxitoxins）, making blooms of this species a serious health concern for humans. In the last 10 15 years, there has been a considerable body of research conducted on the ecology, physiology and toxin production of this species and this paper reviews these studies with a focus on the cylindrospermopsin （cYN）-producing strains. c. raciborskii has low light requirements, close to neutral buoyancy, and a wide temperature tolerance, giving it the capacity to grow in many lentic waterbodies. It also has a flexible strategy with respect to nitrogen （N） utilisation; being able to switch between utilising fixed and atmospheric N as sources of N fluctuate. Additionally this species has a high phosphate （DIP） affinity and storage capacity. Like many cyanobacteria, it also has the capacity to use dissolved organic phosphorus （DOP）. changes in nutrient concentrations, light levels and temperature have also been found to affect production of the toxin cYN by this species. However, optimal toxin production does not necessarily occur when growth rates are optimal. Additionally, different strains of c. raciborskii vary in their cell quota of cYN, making it difficult to predict toxin concentrations, based on c. raciborskii cell densities. In summary, the ecological flexibility of this organism means that controlling blooms of c. raciborskii is a difficult undertaking. However, improved understanding of factors promoting the species and toxin production by genetically capable strains will lead to improved predictive models of blooms.

关键词： cyanobacteria freshwater algal toxins nutrients light temperature