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Rationalizing phonon dispersion for lattice thermal conductivity of solids

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National Science Review 2018年第6期5卷 888-894页

作者： Zhiwei Chen Xinyue Zhang Siqi Lin Lidong Chen Yanzhong Pei Interdisciplinary Materials Research Center School of Materials Science and Engineering Tongji University State Key Lab of High Performance Ceramics & Superfine Microstructures Shanghai Institute of Ceramics Chinese Academy of Sciences

Lattice thermal conductivity(κL) is one of the most fundamental properties of solids. The acoustic–elastic-wave assumption, proposed by Debye(Debye P. Ann Phys 1912; 344: 789–839), has led to linear phonon dispersion being the most common approximation for understanding phonon transport over the past century. Such an assumption does not take into account the effect of a periodic boundary condition on the phonon dispersion, originating from the nature of periodicity on atomic arrangements. Driven by modern demands on the thermal functionality of materials, with κLranging from ultra-low to ultra-high,any deviation from the Debye approximation in real materials becomes more and more significant. This work takes into account the periodic boundary condition, and therefore rationalizes the phonon dispersion to be more realistic. This significantly improves the precision for quickly predicting κLwithout any fitting parameters, as demonstrated in hundreds of materials, and offers a theoretical basis rationalizing κLto be lower than the minimum currently accepted based on the Debye dispersion. This work paves the way for designing solids with expected κLand particularly inspires the advancement of low-κLmaterials for thermal energy applications.

关键词： thermoelectric thermal conductivity minimal thermal conductivity phonon dispersion

High-pressure phonon dispersion of copper by using the modified analytic embedded atom method

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Chinese Physics B 2013年第9期22卷 520-524页

作者：张晓军陈长乐凤飞龙 Shaanxi Key Laboratory of Condensed Matter Structures and Properties and Key Laboratory of Space Applied Physics and Chemistry Ministry of EducationNorthwestern Polytechnical University School of Science Xi'an Polytechnic University

By using the Born-von Kfirmfin theory of lattice dynamics and the modified analytic embedded atom method, we reproduce the experimental results of the phonon dispersion in fcc metal Cu at zero pressure along three high symmetry directions and four oft-symmetry directions, and then simulate the phonon dispersion curves of Cu at high pressures of 50, 100, and 150 GPa. The results show that the shapes of dispersion curves at high pressures are very similar to that at zero pressure. All the vibration frequencies of Cu in all vibration branches at high pressures are larger than the results at zero pressure, and increase correspondingly as pressure reaches 50, 100, and 150 GPa sequentially. Moreover, on the basis of phonon dispersion, we calculate the values of specific heat of Cu at different pressures. The prediction of thermodynamic quantities lays a significant foundation for guiding and judging experiments of thermodynamic properties of solids under high pressures.

关键词： phonon dispersion high pressure simulation modified analytic embedded atom method

An ab initio investigation of vibrational, thermodynamic, and optical properties of Sc_2AlC MAX compound

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Chinese Physics B 2016年第10期25卷 103-108页

作者： M A Ali M T Nasir M R Khatun A K M A Islam S H Naqib Department of Physics Chittagong University of Engineering and Technology Department of Arts & Sciences Bangladesh Army University of Science and Technology Department of Physics University of Rajshahi International Islamic University Chittagong

The structural vibrational, thermodynamical, and optical properties of potentially technologically important, weakly coupled MAX compound, Sc2 Al C are calculated using density functional theory(DFT). The structural properties of ScAlC are compared with the results reported earlier. The vibrational, thermodynamical, and optical properties are theoretically estimated for the first time. The phonon dispersion curve is calculated and the dynamical stability of this compound is investigated. The optical and acoustic modes are observed clearly. We calculate the Helmholtz free energy(F), internal energy(E), entropy(S), and specific heat capacity(Cv) from the phonon density of states. Various optical parameters are also calculated. The reflectance spectrum shows that this compound has the potential to be used as an efficient solar reflector.

关键词： MAX compound phonon dispersion thermodynamical properties optical properties

The electronic structures, Born effective charge tensors,and phonon properties of cubic, tetragonal,orthorhombic, and rhombohedral K_(0.5)Na_(0.5)NbO_3: A first-principles comparative study

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Chinese Physics B 2014年第12期23卷 390-397页

作者：周树兰赵显江向平韩晓东 Department of Material Science and Engineering Jingdezhen Ceramics Institute State Key Laboratory of Crystal Material Institute of Crystal Material Shandong University

The electronic structures, Born effective charges（BECs）, and full phonon dispersions of cubic, tetragonal, orthorhombic, and rhombohedral K0.5Na0.5Nb O3 are investigated by the first principles method based on density functional *** hybridized states of Nb 4d and O 2p states are observed in the valence band, showing the formation of a strong Nb–O covalent bond which should be responsible for the displacement of Nb and O atoms. The abnormally large BECs of Nb and O indicate the possibility of phase instability induced by the off-center displacement of Nb and O atoms. The phonon dispersions reveal that the ferroelectric instability of K0.5Na0.5Nb O3 is dominated by Nb and O displacements with significant Na characteristics. In addition to the ferroelectric instability, there is also rotational instability coming from the oxygen octahedra rotation around one axis. Moreover, the Γ phonon properties of orthorhombic KNb O3, Na Nb O3, and K0.5Na0.5Nb O3 are also studied in detail.

关键词： Born effective charge phonon dispersion density functional theory(DFT) phase instability of K0.5Na0.5NbO3

High Pressure Structural Instability and Thermal Properties of Rutile TiO2 from First-principles

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Chinese Journal of Chemical Physics 2014年第1期27卷 69-74,I0004页

作者：胡翠娥曾召益孔春阳崔玉亭张林蔡灵仓重庆师范大学物理与电子工程学院重庆400047 中国工程物理研究院流体物理研究所冲击波与爆轰物理国防科技重点实验室绵阳621900

We report a first-principles calculation to investigate the structural instability of rutile TiO2. The high pressure structural parameters are well reproduced. The calculated phonon disper-sion curves agree with experiments at zero pressure. Under compression, we capture a large softening around Γ point, which indicates the structural instability. From the high pressure elastic constants, we find that the rutile TiO2 is unstable when the applied pressure is larger than 17.7 GPa. Within the quasi-harmonic approximation, the thermal equation of state, thermal expansion oefficient, bulk modulus, and entropy are well reproduced. The thermal properties confirm the available experimental data and are extended to a wider pressure and temperature range.

关键词： TiO2 phonon dispersion Thermodynamics Density functional theory

Programmable repulsive potential for tight-binding from Chen-Möbius inversion theorem

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 71-83页

作者： Jian-Gao Li Jin-Kun Tang Hong-Quan Song Gotthard Seifert Dong-Bo Zhang College of Nuclear Science and Technology Beijing Normal UniversityBeijing 100875China Department of Physics Beijing Normal UniversityBeijing 100875China College of Physics and Telecommunication Engineering Zhoukou Normal UniversityZhoukou 466001China Theoretische Chemie Technische Universität DresdenDresden D-01062Germany

An accurate total energy calculation is essential in materials *** date,many tight-binding(TB)approaches based on parameterized hopping can produce electronic structures comparable to those obtained using first-principles ***,TB approaches still have limited applicability for determining material properties derived from the total *** is,the predictive power of the TB total energy is impaired by an inaccurate evaluation of the repulsive *** complexity associated with the parametrization of TB repulsive potentials is the weak link in this *** this study,we propose a new method for obtaining the pairwise TB repulsive potential for crystalline materials by employing the Chen-Möbius inversion *** show that the TB-based phonon dispersions,calculated using the resulting repulsive potential,compare well with those obtained by first-principles calculations for various systems,including covalent and ionic bulk materials and twodimensional *** present approach only requires the first-principles total energy and TB electronic band energy as input and does not involve any *** striking feature enables us to generate repulsive potentials programmatically.

关键词： tight binding first-principles calculation total energy repulsive potential phonon dispersion

Novel structures and mechanical properties of Zr_(2)N:Ab initio description under high pressures

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Chinese Physics B 2021年第1期30卷 434-442页

作者： Minru Wen Xing Xie Zhixun Xie Huafeng Dong Xin Zhang Fugen Wu Chong-Yu Wang School of Physics and Optoelectronic Engineering Guangdong University of TechnologyGuangzhou 510006China School of Materials and Energy Guangdong University of TechnologyGuangzhou 510006China Department of Physics Tsinghua UniversityBeijing 100084China

With the formation of structural vacancies,zirconium nitrides(key materials for cutting coatings,super wearresistance,and thermal barrier coatings) display a variety of compositions and phases featuring both cation and nitrogen *** study presents a systematic exploration of the stable crystal structures of zirconium heminitride combining the evolutionary algorithm method and ab initio density functional theory calculations at pressures of 0 GPa,30 GPa,60 GPa,90 GPa,120 GPa,150 GPa,and 200 *** addition to the previously proposed phases P42/mnm-,Pnnn-,and Cmcm-Zr2 N,five new high-pressure Zr_(2)N phases of PA/nmm,IA/mcm,P2_(1)/m,P3 m1,and C2/m are *** enthalpy study of these candidate configurations reveals various structural phase transformations of Zr2 N under *** calculating the elastic constants and phonon dispersion,the mechanical and dynamical stabilities of all predicted structures are examined at ambient and high *** understand the structure-property relationships,the mechanical properties of all Zr_(2)N compounds are investigated,including the elastic moduli,Vickers hardness,and directional dependence of Young’s *** Cmncm-Zr2 N phase is found to belong to the brittle materials and has the highest Vickers hardness(12.9 GPa) among all candidate phases,while the I4/mcm-Zr2 N phase is the most ductile and has the lowest Vickers hardness(2.1 GPa).Furthermore,the electronic mechanism underlying the diverse mechanical behaviors of Zr2 N structures is discussed by analyzing the partial density of states.

关键词： phase transition phonon dispersion Zr_(2)N first-principles calculations

Graphene-based thermal modulators

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Nano Research 2015年第8期8卷 2755-2762页

作者： Xiangjun Liu Gang Zhang Yong-Wei Zhang Institute of High Performance Computing A＊STAR Singapore 138632 Singapore

The quest for materials and devices that are capable of controlling heat flux continues to fuel research on thermal controlling devices. In this letter, using molecular dynamics simulations, we demonstrate that a partially clamped singlelayer graphene can serve as a thermal modulator. The mismatch in phonon dispersion between the unclamped and clamped graphene sections results in phonon interface scattering, and the strength of interface scattering is tunable by controlling the clamp-graphene distance via applying the external pressure. Owing to the ultra-thin structure of graphene and its highly sensitive phonon dispersion to external physical interaction, the modulation efficiency--which is defined as the ratio of the highest to lowest heat flux-can reach as high as 150% at a moderate pressure of 50 GPa. This modulation efficiency can be further enhanced by arranging a number of clamps in series along the direction of the heat flux.

关键词： graphene thermal modulator molecular dynamics thermal conductivity phonon dispersion

Phase Transition and phonon Spectrum of Zinc-Blende Structure ZnX (X=S, Se,Te)

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Communications in Theoretical Physics 2010年第6期53卷 1160-1166页

作者：谭嘉进姬广富陈向荣芶清泉 Institute of Atomic and Molecular Physics Sichuan University National Key Laboratory of Shock Wave and Detonation Physics Chinese Academy of Engineering Physics International Centre for Materials Physics Chinese Academy of Sciences

Calculations have been performed to investigate the pressure-induced solid-solid phase transitions and the mechanical stability for three zinc-blende II-VI semiconductor compounds： ZnS, ZnSe, ZnTe by ab initio plane-wave pseudopotential density functional theory （DFT）. Using the generalized gradient approximation （GGA） for exchange and correlation in the scheme of Perdew-Wang 1991 （P Wgl ）, the ground state properties and equation of state are obtained, which are well consistent with the experimental data available and other calculations. On the basis of the forth-order Birch-Murnaghan equation of states, the transition pressures Pt are determined through the analysis of enthalpy variation with pressure. A linear-response approach is used to calculate the frequencies of the phonon dispersion. Finally, by the calculations of phonon frequencies, some thermodynamic properties such as the vibrational contribution to the Helmholtz free energy （F）, enthedpy （H）, entropy （S）, and the heat capacity （Cv ） are also successfully obtained.

关键词： phase transition elasticity phonon dispersion