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Comparative first-principles study of elastic constants of covalent and ionic materials with LDA,GGA,and meta-GGA functionals and the prediction of mechanical hardness

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Science China(Technological Sciences) 2021年第12期64卷 2755-2761页

作者： XING WanDong MENG FanYan NING JinLiang SUN JianWei YU Rong Department of Physics University of Science and Technology BeijingBeijing 100083China National Center for Electron Microscopy in Beijing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Department of Physics and Engineering Physics Tulane UniversityNew OrleansLA 70118USA

Accurate prediction of single-crystal elastic constants is critical for materials design and for understanding phase transition and elastic interactions in materials.In this work,the accuracy of elastic constants calculated with three density functional approximations has been compared,including the local density approximation(LDA),the generalized gradient approximation(GGA),and the recently developed strongly constrained and appropriately normed(SCAN)meta-GGA.The results show that SCAN and PBE describe elastic constants better than LDA.The strong correlation between the mechanical hardness and the stiffness of the softest eigenmode(SSE)has been given for above three density functionals.The correlation is capable of predicting accurately the hardness of covalent,ionic,and mixed covalent-ionic crystals,and providing us a convenient indicator for the discovery of hard or superhard materials.

关键词： hardness indicator elastic constants stiffness of softest eigenmode superhard materials

Ground state parameters,electronic properties and elastic constants of CaMg3:DFT study

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Journal of Magnesium and Alloys 2020年第4期8卷 1166-1175页

作者： H.Rekab-Djabri Manal M.Abdus Salam S.Daoud M.Drief Y.Guermit S.Louhibi-Fasla Laboratory of Micro and Nanophysics(LaMiN) National Polytechnic School OranENPO-MABP 1523El M'Naouer31000 OranAlgeria Faculty of Nature and Life Sciences and Earth Sciences Akli Mohand-Oulhadj University10000 BouiraAlgeria Department of Applied Physics Tafila Technical UniversityTafila 66110Jordan Laboratory of Materials and Electronic Systems Mohamed El Bachir El Ibrahimi University of Bordj Bou ArreridjBordj BouArreridj 34000Algeria Laboratoire des Materiaux Magnetiques Departement de PhysiqueFaculte des SciencesUniversite Djilali LIABES de Sidi-Bel-AhbesSidi Bel Abbes 22000Algeria

The present study aims to investigate the equation of state(EOS)parameters of CaMg3 in aReCh(D09),AIFR(DO3),CU3A11(LI2)and CuTi3(L60)structures,using full potential linear muffin-tin orbitals(FP-LMTO)approach based on the density functional theory(DFT).The local density approximation(LDA)and the generalized gradient approximation(GGA)were both applied for the exchange-correlation potential term.The calculated equation of slate parameters at equilibrium,in general,agreed well with the available data of the literature.The calculations showed that under compression CaMg3 transforms from DO3 to DO9 at about 29.96GPa,and 25.1 GPa using LDA and GGA,respectively.The elastic constants C,y,aggregate moduli,Vickers hardness,sound velocity,and Debye temperature of CaMg3 in D03 structure were also reported,discussed and analyzed.Using LDA(GGA),the calculated values of Hv andθD were found at around 5.80GPa(5.93GPa)and 393.44 K(389.91 K),respectively.Electronic band structure,total density of states(TDOS)as well as the partial density of states(PDOS)have been also obtained.The electronic band structure confirms the metallic behavior of CaMg3 in DO3 phase,the valence bands are dominated by the maximum contribution of‘d’like states of Ca in the energy ranging from 2 to 3 eV for GGA,and from 4.5 to 5 eV for LDA,respectively.

关键词： CaMg3 compound Electronic properties Phase transition elastic constants FP-LMTO

elastic constants characterization on graphite at 500℃ by the virtual fields method

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Theoretical & Applied Mechanics Letters 2014年第2期4卷 59-65页

作者： Baoqiao Guo Huaixi Wang Huimin Xie Pengwan Chen State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology AML Department of Engineering Mechanics Tsinghua University

In this paper the elastic constants of graphite at elevated temperature were experimentally investigated by using the virtual fields method （VFM）. A new method was presented for the characterization of mechanical properties at elevated temperature. The three-point bending tests were performed on graphite materials by an universal testing machine equipped with heating fumace. Based on the heterogeneous deformation fields measured by the digital image correlation （DIC） technique, the elastic constants were then extracted by using VFM. The measurement results of the elastic constants at 500℃ were obtained. The ef- fect on the experimental results was also analyzed. The successful results verify the feasibility of using the proposed method to measure the properties of graphite at high temperature, and the proposed method is believed to have a good potential for further applications.

关键词： elastic constants graphite high temperature digital image correlation virtualfields method

Macroscopic elastic constants of Pure Metal Based on the Interactions between Microscopic Particles

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Chinese Journal of Mechanical Engineering 2013年第2期26卷 356-364页

作者： LU Ming NIU Yongsheng FAN Rui School of Mechanical & Electronic Engineering Zhongyuan University of Technology

The research activities of the calculation of the elastic constants of metal are mainly focused on the elastic constants of crystal at the micro level. To the calculation of the macroscopic elastic constants of metal, although molecular dynamics method and quasicontinuum method can be used, but there are shortcomings in them, such as a large amount of computation and that the spatial scale of the study model is limited. Therefore, with a pure metal thin plate composed of a single layer of microscopic particles as research object, a new mechanical model is established after the interactions between microscopic particles of the thin plate are applied on the continuum mechanics model of the thin plate. According to this model, the calculation formulas for the microscopic elastic constants, which are the elastic constants of any triangle region in the model, are obtained. After the concept of the ideal micro structure is presented, the calculation formulas for the macroscopic elastic constants, the elastic modulus and the Poisson’s ratio of pure metal are obtained, where the Poisson＇s ratio is the constant that is equal to 1？3. As an example, the elastic constants and the elastic modulus of pure copper are solved, where c11 is 175.811 GPa, c12 is 58.604 GPa, c33 is 58.604 GPa and E is 156.277 GPa, the rationality and the correctness of the model are verified. The model presented fully embodies the discreteness of the microstructure of solid, is a development to the continuum model, and is more suitable to reality, more simplified and more new to the study of the macroscopic elastic constants of pure metal.

关键词： pure metal elastic constants interaction mechanical model microscopic particle

First-principles study of the elastic constants and optical properties of uranium metal

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Chinese Physics B 2012年第8期21卷 503-510页

作者：陈秋云谭世勇赖新春陈军 Science and Technology on Surface Physics and Chemistry Laboratory

We perform first-principles calculations of the lattice constants, elastic constants, and optical properties for alpha- and gamma-uranium based on the ultra-soft pseudopotential method. Lattice constants and equilibrium atomic volume are consistent pretty well with the experimental results. Some difference exists between our calculated elastic constants and the experimental data. Based on the satisfactory ground state electronic structure calculations, the optical co ductivity, dielectric function, refractive index, and extinction coefficients are also obtained. These calculated optical properties are compared with our results and other published experimental data.

关键词： uranium electronic structure elastic constants optical properties

A Calculation Approach to elastic constants of Crystallines at High Pressure and Finite Temperature

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Chinese Physics Letters 2002年第9期19卷 1319-1321页

作者：向士凯经福谦等 LaboratoryforShockWaveandDetonationPhysicsResearch SouthwestInstituteofFluidPhysicsPOBox919-111Mianyang621900 LaboratoryforShockWaveandDetonationPhysicsResearch SouthwestInstituteofFluidPhysicsPOBo

elastic constants of Na and Li metals are calculated successfully for temperatures up to 350K and pressures up to 30GPa using a scheme without involving any adjustable parameter. elastic constants areassumed to depend only on an effective pair potential that is only determined by the average interatomic distance. Temperature has aneffect on elastic constants by way of charging the equilibrium. The elastic constants can be obtained by fitting the relationship betweentotal energy and strain tensor using the new set of lattice parameters obtained by calculating displacement of atoms at the finite temperatureand at a fixed pressure. The relationship between the effective pair potential and the interatomic distance is fitted by using a series ofdata of cohesive energy corresponding to lattice parameters.

关键词： strain tensor Finite REACTOR LATTICE PARAMETERS Temperature CONSTANT PRESSURE Pair potential lattice parameters Cohesive energy elastic constants high pressure

THE DEVELOPMENT OF A GENERAL ANISOTROPIC MATERIAL MODEL WITH RESONANT ULTRASOUND SPECTROSCOPY TECHNOLOGY FOR THE MEASUREMENT OF elastic constants OF PIEZOELECTRIC CRYSTALS

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THE DEVELOPMENT OF A GENERAL ANISOTROPIC MATERIAL MODEL WITH...

THE MEASUREMENT OF elastic constants OF QUARTZ CRYSTAL BY RESONANT ULTRASOUND SPECTROSCOPY

2013全国压电和声波理论及器件技术研讨会

作者： Zhen WANG Ji WANG Yanqing ZHENG Fapeng YU Sergei ZHGOON Tingfeng MA Piezoelectric Device Laboratory School of Mechanical Engineering & MechanicsNingbo University Shanghai Institute of Ceramics Chinese Academy of Sciences State Key Laboratory of Crystal Materials and Institute of Crystal Materials Shandong University National research University Moscow Power Engineering Institute

The mechanical resonant response of a solid depends on its shape,density,and elastic moduli.We describe here the computational methods based on a general anisotropic material model for obtaining and analyzing the resonant frequencies of small samples,and provide examples to demonstrate the utilization and validation.Two new material types with six and thirteen independent elastic constants are formulated and tested with the instrumentation.This study will lead to expansion of software capability for the testing of novel materials with current instrumentation.

关键词： elastic constants RUSpec Technology Quartz Crystal Levenberg-Marquardt Method

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THE MEASUREMENT OF ELASTIC CONSTANTS OF QUARTZ CRYSTAL BY RE...

CHARACTERIZATIONS OF elastic constants OF TRANSPARENT THIN FILMS DEPOSITED ON SUBSTRATES BY LASER ULTRASONIC METHOD

2012全国压电和声波理论及器件技术研讨会

作者： Zhen WANG Ji WANG Xiang-wu XU Jian-ke DU Ting-feng MA Piezoelectric Device Laboratory School of Mechanical Engineering ＆ MechanicsNingbo University

The mechanical resonant response of a solid depends on its shape,density,and elastic moduli.We describe here the instrumentation and computational methods for obtaining and analyzing the resonant frequency of very small（0.001 cm3）samples,and provide examples to demonstrate the utilization of the technique.A new material type with six independent elastic constants are formulated and tested with the instrumentation.This study will leads to expansion of the software capability for the testing of novel materials.

关键词： elastic constants Resonant Ultrasound Spectroscopy Quartz crystal Levenberg-Marquardt method

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CHARACTERIZATIONS OF ELASTIC CONSTANTS OF TRANSPARENT THIN F...