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Thermal conductivity of glasses: first-principles theory and applications

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npj Computational Materials 2023年第1期9卷 1253-1274页

作者： Michele Simoncelli Francesco Mauri nicola marzari Theory of Condensed Matter Group of the Cavendish Laboratory University of CambridgeCambridgeUK Dipartimento di Fisica Universitàdi Roma La SapienzaRomaItaly Theory and Simulation of Materials(THEOS)and National Centre for Computational Design and Discovery of Novel Materials(MARVEL) École Polytechnique Fédérale de LausanneLausanneSwitzerland

Predicting the thermal conductivity of glasses from first principles has hitherto been a very complex problem.The established Allen-Feldman and Green-Kubo approaches employ approximations with limited validity—the former neglects anharmonicity,the latter misses the quantum Bose-Einstein statistics of vibrations—and require atomistic models that are very challenging for first-principles methods.Here,we present a protocol to determine from first principles the thermal conductivityκ(T)of glasses above the plateau(i.e.,above the temperature-independent region appearing almost without exceptions in theκ(T)of all glasses at cryogenic temperatures).The protocol combines the Wigner formulation of thermal transport with convergence-acceleration techniques,and accounts comprehensively for the effects of structural disorder,anharmonicity,and Bose-Einstein statistics.We validate this approach in vitreous silica,showing that models containing less than 200 atoms can already reproduceκ(T)in the macroscopic limit.We discuss the effects of anharmonicity and the mechanisms determining the trend ofκ(T)at high temperature,reproducing experiments at temperatures where radiative effects remain negligible.

关键词： glasses conductivity harmonic

Automated mixing of maximally localized Wannier functions into target manifolds

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npj Computational Materials 2023年第1期9卷 229-237页

作者： Junfeng Qiao Giovanni Pizzi nicola marzari Theory and Simulations of Materials(THEOS) and National Centre for Computational Design and Discovery of Novel Materials(MARVEL)École Polytechnique Fédérale de Lausanne1015 LausanneSwitzerland Laboratory for Materials Simulations(LMS) Paul Scherrer Institut(PSI)CH-5232 Villigen PSISwitzerland

Maximally localized Wannier functions(MLWFs)are widely used in electronic-structure calculations.We have recently developed automated approaches to generate MLWFs that represent natural tight-binding sets of atomic-like orbitals;these describe accurately both the occupied states and the complementary unoccupied ones.For many applications,it is required to use MLWFs that describe instead certain target groups of bands:the valence or the conduction bands,or correlated manifolds.Here,we start from these tight-binding sets of MLWFs,and mix them using a combination of parallel transport and maximal localization to construct manifold-remixed Wannier functions(MRWFs):these are orthogonal sets of MLWFs that fully and only span desired target submanifolds.The algorithm is simple and robust,and is showcased here in reference applications(silicon,MoS_(2),and SrVO_(3))and in a mid-throughput study of 77 insulators.

关键词： maximal bands occupied

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 polarization.We 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 ferroelectric.The 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 modeling.These predictions allow us to assess the microscopic mechanism of the ferroelectric transition.The 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 phases.Moreover,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 transition.Finally,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

Solids that are also liquids: elastic tensors of superionic materials

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npj Computational Materials 2023年第1期9卷 2252-2264页

作者： Giuliana Materzanini Tommaso Chiarotti nicola marzari Theory and Simulations of Materials(THEOS) École Polytechnique Fédérale de LausanneCH-1015 LausanneSwitzerland National Centre for Computational Design and Discovery of Novel Materials(MARVEL) École Polytechnique Fédérale de LausanneCH-1015 LausanneSwitzerland Present address:Institute of Condensed Matter and Nanosciences UniversitéCatholique de LouvainB-1348 Louvain-la-NeuveBelgium

Superionics are fascinating materials displaying both solid- and liquid-like characteristics: as solids, they respond elastically to shearstress;as liquids, they display fast-ion diffusion at normal conditions. In addition to such scientific interest, superionics aretechnologically relevant for energy, electronics, and sensing applications. Characterizing and understanding their elastic propertiesis, e.g., urgently needed to address their feasibility as solid-state electrolytes in all-solid-state batteries. However, static approachesto elasticity assume well-defined reference positions around which atoms vibrate, in contrast with the quasi-liquid motion of themobile ions in fast ionic conductors. Here, we derive the elastic tensors of superionics from ensemble fluctuations in the isobaric-isothermal ensemble, exploiting extensive Car-Parrinello simulations. We apply this approach to paradigmatic Li-ion conductors,and complement with a block analysis to compute statistical errors. Static approaches sampled over the trajectories oftenoverestimate the response, highlighting the importance of a dynamical treatment in determining elastic tensors in superionics.

关键词： ionic liquids ensemble

Projectability disentanglement for accurate and automated electronic-structure Hamiltonians

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npj Computational Materials 2023年第1期9卷 215-228页

Maximally-localized Wannier functions(MLWFs)are broadly used to characterize the electronic structure of materials.Generally,one can construct MLWFs describing isolated bands(e.***.valence bands of insulators)or entangled bands(e.***.valence and conduction bands of insulators,or metals).Obtaining accurate and compact MLWFs often requires chemical intuition and trial and error,a challenging step even for experienced researchers and a roadblock for high-throughput calculations.Here,we present an automated approach,projectability-disentangled Wannier functions(PDWFs),that constructs MLWFs spanning the occupied bands and their complement for the empty states,providing a tight-binding picture of optimized atomic orbitals in crystals.Key to the algorithm is a projectability measure for each Bloch state onto atomic orbitals,determining if that state should be kept identically,discarded,or mixed into the disentanglement.We showcase the accuracy on a test set of 200 materials,and the reliability by constructing 21,737 Wannier Hamiltonians.

关键词： bands Hamiltonian electronic

General invariance and equilibrium conditions for lattice dynamics in 1D,2D,and 3D materials

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npj Computational Materials 2022年第1期8卷 2280-2290页

作者： Changpeng Lin Samuel Poncé nicola marzari Theory and Simulation of Materials(THEOS) École Polytechnique Fédérale de LausanneCH-1015LausanneSwitzerland National Centre for Computational Design and Discovery of Novel Materials(MARVEL) École Polytechnique Fédérale de LausanneCH-1015LausanneSwitzerland European Theoretical Spectroscopy Facility Institute of Condensed Matter and NanosciencesUniversitécatholique de LouvainChemin desÉtoiles 8B-1348Louvain-la-NeuveBelgium

The long-wavelength behavior of vibrational modes plays a central role in carrier transport,phonon-assisted optical properties,superconductivity,and thermomechanical and thermoelectric properties of materials.Here,we present general invariance and equilibrium conditions of the lattice potential;these allow to recover the quadratic dispersions of flexural phonons in low-dimensional materials,in agreement with the phenomenological model for long-wavelength bending modes.We also prove that for any low-dimensional material the bending modes can have a purely out-of-plane polarization in the vacuum direction and a quadratic dispersion in the long-wavelength limit.In addition,we propose an effective approach to treat invariance conditions in crystals with non-vanishing Born effective charges where the long-range dipole-dipole interactions induce a contribution to the lattice potential and stress tensor.Our approach is successfully applied to the phonon dispersions of 158 two-dimensional materials,highlighting its critical relevance in the study of phonon-mediated properties of low-dimensional materials.

关键词： materials. lattice invariance

Risk of hepatitis B virus reactivation in oncological patients treated with tyrosine kinase inhibitors:A case report and literature analysis

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World Journal of Gastroenterology 2024年第9期30卷 1253-1256页

作者： Francesca Colapietro nicola Pugliese Antonio Voza Alessio Aghemo Stella De nicola Department of Biomedical Sciences Humanitas UniversityMilan 20072Italy Division of Internal Medicine and Hepatology Department of GastroenterologyHumanitas Research HospitalMilan 20089Italy Department of Emergency Humanitas Research HospitalMilan 20089Italy

Hepatitis B virus(HBV)reactivation(HBVr)represents a severe and potentially life-threatening condition,and preventive measures are available through blood test screening or prophylactic therapy administration.The assessment of HBVr traditionally considers factors such as HBV profile,including hepatitis B surface antigen(HBsAg)and antibody to hepatitis B core antigen,along with type of medication(chemotherapy;immunomodulants).Nevertheless,consideration of possible patient’s underlying tumor and the specific malignancy type(solid or hematologic)plays a crucial role and needs to be assessed for decision-making process.

关键词： Chronic hepatitis B Reactivation Nucleoside analogue Tyrosine kinase inhibitors Onco-hematology

Increased number of symptoms during the acute phase of SARS-CoV-2 infection in athletes is associated with prolonged time to return to full sports performance—AWAREⅧ

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Journal of Sport and Health Science 2024年第3期13卷 280-287,I0001页

作者： Carolette Snyders Marlise Dyer nicola Sewry Esme Jordaan Martin Schwellnus Sport Exercise Medicine and Lifestyle Institute(SEMLI)Faculty of Health SciencesUniversity of PretoriaPretoria 0083South Africa Section Sports Medicine Faculty of Health SciencesUniversity of PretoriaPretoria 0083South Africa IOC Research Centre of South Africa Pretoria 0083South Africa Biostatistics Unit South African Medical Research CouncilTygerberg 7505South Africa Statistics and Population Studies Department University of the Western CapeCape Town 7535South Africa

Purpose The aim of the study was to identify factors associated with prolonged time to return to full performance(RTFP)in athletes with recent severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection.Methods Prospective cohort study with cross sectional analysis.A total of 84 athletes with confirmed SARS-CoV-2 infection assessed at a coronavirus disease 2019 recovery clinic gave a history of age,sex,type/level of sport,co-morbidities,pre-infection training hours,and 26 acute SARS-CoV-2 symptoms from 3 categories(“nose and throat”,“chest and neck”,and“whole body”/systemic).Data on days to RTFP were obtained by structured interviews.Factors associated with RTFP were demographics,sport participation,history of co-morbidities,pre-infection training history,and acute symptoms(type,number).Outcomes were:(a)days to RTFP(median,interquartile range(IQR))in asymptomatic(n=7)and symptomatic athletes(n=77),and(b)hazard ratios(HRs;95%confidence interval)for symptomatic athletes with vs.without a factor(univariate,multiple models).HR0.05).Factors associated with prolonged RTFP(univariate models)were:females(HR=0.57;p=0.014),endurance athletes(HR=0.41;p<0.0001),co-morbidity number(HR=0.75;p=0.001),and respiratory disease history(HR=0.54;p=0.026).In symptomatic athletes,prolonged RTFP(multiple models)was significantly associated with increased“chest and neck”(HR=0.85;p=0.017)and“nose and throat”(HR=0.84;p=0.013)symptoms,but the association was more profound between prolonged RFTP and increased total number of“all symptoms”(HR=0.91;p=0.001)and“whole body”/systemic(HR=0.82;p=0.007)symptoms.Conclusion A larger number of total symptoms and specifically“whole body”/systemic symptoms during the acute phase of SARS-CoV-2 infection in athletes is associated with prolonged RTFP.

关键词： Athletes COVID-19 Performance Recovery Return to play

A high-order target phase approach for the station-keeping of periodic orbits

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Astrodynamics 2024年第1期8卷 61-75页

作者： Xiaoyu Fu nicola Baresi Roberto Armellin Surrey Space Centre University of SurreyGuildfordGU27XHUK Te PūnahaĀtea-Auckland Space Institute University of AucklandAuckland1010New Zealand

A novel high-order target phase approach(TPhA)for the station-keeping of periodic orbits is proposed in this work.The key elements of the TPhA method,the phase-angle Poincare map and high-order maneuver map,are constructed using differential algebra(DA)techniques to determine station-keeping epochs and calculate correction maneuvers.A stochastic optimization framework tailored for the TPhA-based station-keeping process is leveraged to search for fuel-optimal and error-robust TPhA parameters.Quasi-satellite orbits(QSOs)around Phobos are investigated to demonstrate the efficacy of TPhA in mutli-fidelity dynamical models.Monte Carlo simulations demonstrated that the baseline QSO of JAXA’s Martian Moons eXploration(MMX)mission could be maintained with a monthly maneuver budget of approximately 1 m/s.

关键词： target phase approach(TPhA) station-keeping Poincarémap differential algebra(DA) quasi-satellite orbit(QSO)