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Million-scale data integrated deep neural network for phonon properties of heuslers spanning the periodic table

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npj Computational Materials 2023年第1期9卷 2155-2166页

作者： Alejandro Rodriguez Changpeng Lin Hongao Yang Mohammed Al-Fahdi Chen Shen Kamal Choudhary Yong Zhao Jianjun Hu Bingyang Cao Hongbin Zhang Ming Hu Department of Mechanical Engineering University of South CarolinaColumbiaSC 29208USA Theory and Simulation of Materials(THEOS) École Polytechnique Fédérale de LausanneCH-1015 LausanneSwitzerland Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing 100084China Institute of Materials Science Technical University of DarmstadtDarmstadt 64287Germany Materials Science and Engineering Division National Institute of Standards and TechnologyGaithersburgMD 20899USA Department of Computer Science and Engineering University of South CarolinaColumbiaSC 29208USA

Existing machine learning potentials for predicting phonon properties of crystals are typically limited on a material-to-materialbasis, primarily due to the exponential scaling of model complexity with the number of atomic species. We address this bottleneckwith the developed Elemental Spatial Density Neural Network Force Field, namely Elemental-SDNNFF. The effectiveness andprecision of our Elemental-SDNNFF approach are demonstrated on 11,866 full, half, and quaternary Heusler structures spanning 55elements in the periodic table by prediction of complete phonon properties. Self-improvement schemes including active learningand data augmentation techniques provide an abundant 9.4 million atomic data for training. Deep insight into predicted ultralowlattice thermal conductivity (<1 Wm^(−1) K^(−1)) of 774 Heusler structures is gained by p–d orbital hybridization analysis. Additionally, aclass of two-band charge-2 Weyl points, referred to as “double Weyl points”, are found in 68% and 87% of 1662 half and 1550quaternary Heuslers, respectively.

关键词： properties phonon spanning

Exploring anharmonic lattice dynamics and dielectric relations in niobate perovskites from first-principles self-consistent phonon calculations

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npj Computational Materials 2023年第1期9卷 757-766页

作者： Kwangrae Kim Woohyun Hwang Seung-Hyun Victor Oh Aloysius Soon Department of Materials Science&Engineering Yonsei UniversitySeoul 03722Republic of Korea

Group I niobates(KNbO_(3) and NaNbO_(3))are promising lead-free alternatives for high-performance energy storage applications.Despite their potential,their complex phase transitions arising from temperature-dependent phonon softening and anharmonic effects on dielectric properties remain poorly explored.In this study,we employ density-functional theory(DFT)and self-consistent phonon(SCP)calculations to investigate finite-temperature phonons in cubic niobate perovskites.To include explicit anharmonic vibrational effects,SCP frequencies are shifted by the bubble self-energy correction within the quasiparticle(QP)approximation,providing precise descriptions of phonon softening in these strongly anharmonic solids.We further calculate the static dielectric constant of KNbO_(3) and NaNbO_(3) as a function of temperature using the Lyddane-Sachs-Teller(LST)relation and QP-corrected phonon dispersions.Our theoretical results align with experimental data,offering reliable temperature-dependent phonon dispersions while considering anharmonic self-energies and thermal expansion effects,enhancing our understanding of the complex relations between lattice vibrations and phase transitions in these anharmonic oxides.

关键词： harmonic phonon dielectric

Physics-informed neural networks for solving time-dependent mode-resolved phonon Boltzmann transport equation

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npj Computational Materials 2023年第1期9卷 181-189页

作者： Jiahang Zhou Ruiyang Li Tengfei Luo Department of Aerospace and Mechanical Engineering University of Notre DameNotre DameIN 46556USA Department of Chemical and Biomolecular Engineering University of Notre DameNotre DameIN 46556USA Center for Sustainable Energy at Notre Dame(ND Energy) University of Notre DameNotre DameIN 46556USA

The phonon Boltzmann transport equation(BTE)is a powerful tool for modeling and understanding micro-/nanoscale thermal transport in solids,where Fourier’s law can fail due to non-diffusive effect when the characteristic length/time is comparable to the phonon mean free path/relaxation time.However,numerically solving phonon BTE can be computationally costly due to its high dimensionality,especially when considering mode-resolved phonon properties and time dependency.In this work,we demonstrate the effectiveness of physics-informed neural networks(PINNs)in solving time-dependent mode-resolved phonon BTE.The PINNs are trained by minimizing the residual of the governing equations,and boundary/initial conditions to predict phonon energy distributions,without the need for any labeled training data.The results obtained using the PINN framework demonstrate excellent agreement with analytical and numerical solutions.Moreover,after offline training,the PINNs can be utilized for online evaluation of transient heat conduction,providing instantaneous results,such as temperature distribution.It is worth noting that the training can be carried out in a parametric setting,allowing the trained model to predict phonon transport in arbitrary values in the parameter space,such as the characteristic length.This efficient and accurate method makes it a promising tool for practical applications such as the thermal management design of microelectronics.

关键词： phonon resolved equation

phonon spectroscopy and transport properties of Y_(1-x)Nd_xSr_2Cu_(2.7)Mo_(0.3)O__(7-δ)

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Science China Mathematics 1998年第6期41卷 656-662页

作者：罗培勋赵芸许存义胡克良周贵恩李晓光张裕恒 Structure Research laboratory Deportment of Materials Science and Engineering University of Science and Technology of China Hefei China Anhui Institute of Mechanical and Electrical Engineering Wuhu China World laboratery CCAST Beijing China

The Raman and infrared spectra, resistivity as well as thermoelectric power of Y 1- x Nd x Sr 2Cu 2.7 Mo 0.3 O 7- δ ( x =0, 0.1, 0.2, 0.5, 0.8 and 1.0) are studied carefully. It was found that the structure characteristics of RSr 2Cu 2.7 Mo 0.3 O 7- δ cuprates are different from those of RBa 2Cu 3O 7- δ . The variations of the microstructure in Y 1- x Nd x Sr 2Cu 2.7 Mo 0.3 O 7- δ with Nd doping affect the carrier distribution, so as a result the superconductivity changes. Furthermore, it is pointed out that the microstructure variations with the large rare earth ionic substitution cause the widely existing rare earth ionic size effect in HTSC.

关键词： Y 1- x Nd x Sr 2Cu 2.7 Mo 0.3 O 7- δ rare earth ionic size effect phonon spectroscopy transport properties.

Anharmonic electron-phonon coupling in ultrasoft and locally disordered perovskites

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npj Computational Materials 2023年第1期9卷 744-756页

作者： Marios Zacharias George Volonakis Feliciano Giustino Jacky Even Univ Rennes INSA RennesCNRSInstitut FOTON-UMR 6082F-35000 RennesFrance Univ Rennes ENSCRINSA RennesCNRSISCR-UMR 6226F-35000 RennesFrance Oden Institute for Computational Engineering and Sciences The University of Texas at AustinAustinTX 78712USA Department of Physics The University of Texas at AustinAustinTX 78712USA

Anharmonicity and local disorder(polymorphism)are ubiquitous in perovskite physics,inducing various phenomena observed in scattering and spectroscopy experiments.Several of these phenomena still lack interpretation from first principles since,hitherto,no approach is available to account for anharmonicity and disorder in electron–phonon couplings.Here,relying on the special displacement method,we develop a unified treatment of both and demonstrate that electron–phonon coupling is strongly influenced when we employ polymorphous perovskite networks.We uncover that polymorphism in halide perovskites leads to vibrational dynamics far from the ideal noninteracting phonon picture and drives the gradual change in their band gap around phase transition temperatures.We also clarify that combined band gap corrections arising from disorder,spin-orbit coupling,exchange–correlation functionals of high accuracy,and electron–phonon coupling are all essential.Our findings agree with experiments,suggesting that polymorphism is the key to address pending questions on perovskites’technological applications.

关键词： perovskite phonon harmonic

phonon counting boosts hybrid quantum networks based on optomechanics

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Science China(Physics,Mechanics & Astronomy) 2019年第1期62卷 103-104页

作者： Zhen Shen ChunHua Dong Key Laboratory of Quantum Information University of Science and Technology of China Chinese Academy of Sciences

Recently,optomechanical systems have emerged as promising platforms to perform quantum information processing .There has been considerable progress in the control of solid-state phonons at the quantum level,including the ground state cooling ,the generation of quantum correlated states between radiation fields and mechanical motion ,and mechanical squeezing . A unique feature of the optomechanical systems is the interconversion between stationary and flying (photonic)qubits.Mechanical motion can serve as a universal transducer to mediate the long-range interactions between stationary quantum systems, including trapped ions,superconducting circuits,single charges,and spins in diamond or silicon ,enabling the construction of a hybrid quantum network that combines the otherwise incompatible degrees of the freedom of different physical systems.

关键词： phonon counting Recently optomechanical systems

Primitive to conventional geometry projection for efficient phonon transport calculations

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npj Computational Materials 2023年第1期9卷 365-371页

作者： Xun Li Simon Thébaud Lucas Lindsay Materials Science and Technology Division Oak Ridge National LaboratoryOak RidgeTNUSA Univ Rennes INSA RennesCNRSInstitut FOTON-UMR 6082RennesFrance

The primitive Wigner-Seitz cell and corresponding first Brillouin zone(FBZ)are typically used in calculations of lattice vibrational and transport properties as they contain the smallest number of degrees of freedom and thus have the cheapest computational cost.However,in complex materials,the FBZ can take on irregular shapes where lattice symmetries are not apparent.Thus,conventional cells(with more atoms and regular shapes)are often used to describe materials,though dynamical and transport calculations are more expensive.Here we discuss an efficient anharmonic lattice dynamic method that maps conventional cell dynamics to primitive cell dynamics based on translational symmetries.Such symmetries have not been utilized in typical lattice dynamical calculations.This leads to phase interference conditions that act like conserved quantum numbers and a conservation rule for phonon scattering that is hidden in conventional dynamics which significantly reduces the computational cost.We demonstrate this method for phonon transport in a variety of materials with inputs from first-principles calculations and attribute its efficiency to reduced scattering phase space and fewer summations in scattering matrix element calculations.

关键词： phonon conventional primitive

Managing Quantum Heat Transfer in a Nonequilibrium Qubit-phonon Hybrid System with Coherent phonon States

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Chinese Physics Letters 2021年第1期38卷 10-18页

作者：王晨王鲁钦任捷 Department of Physics Zhejiang Normal UniversityJinhua 321004China Center for phononics and Thermal Energy Science China-EU Joint Center for NanophononicsShanghai Key Laboratory of Special Artificial Microstructure Materials and TechnologySchool of Physics Sciences and EngineeringTongji UniversityShanghai 200092China

We investigate quantum heat transfer in a nonequilibrium qubit-phonon hybrid open system,dissipated by external bosonic thermal reservoirs.By applying coherent phonon states embedded in the dressed quantum master equation,we are capable of dealing with arbitrary qubit-phonon coupling strength.It is counterintuitively found that the effect of negative differential thermal conductance is absent at strong qubit-phonon hybridization,but becomes profound at weak qubit-phonon coupling regime.The underlying mechanism of decreasing heat flux by increasing the temperature bias relies on the unidirectional transitions from the up-spin displaced coherent phonon states to the down-spin counterparts,which seriously freezes the qubit and prevents the system from completing a thermodynamic cycle.Finally,the effects of perfect thermal rectification and giant heat amplification are unraveled,thanks to the effect of negative differential thermal conductance.These results of the nonequilibrium qubit-phonon open system would have potential implications in smart energy control and functional design of phononic hybrid quantum devices.

关键词： phonon quantum coherent

Temperature dependence of biaxial strain and its influence on phonon and band gap of GaN thin film

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Chinese Physics B 2008年第6期17卷 2245-2250页

作者：徐宏妍菅傲群薛晨阳陈阳张斌珍张文栋张志国冯震 Key Laboratory of Instrumentation Science & Dynamic Measurement (North University of China) Ministry of Education National Key Laboratory for Electronic Measurement Technology North University of China The 13th research institute of CETC

Hexagonal GaN epilayer grown on sapphire substrate by metal organic chemical vapour deposition （MOCVD） is studied using Raman scattering and photoluminescence in a temperature range from 100K to 873 K. The model of strain （stress） induced by the different lattice parameters and thermal coefficients of epilayer and substrate as a function of temperature is set up. The frequency and the linewidth of E2^high mode in a GaN layer are modelled by a theory with considering the thermal expansion of the lattice, a symmetric decay of the optical phonons, and the strain （stress） in the layer. The temperature-dependent energy shift of free exeiton A is determined by using Varshni empirical relation, and the effect of strain （stress） is also investigated. We find that the strain in the film leads to a decreasing shift of the phonon frequency and an about 10meV-inereasing shift of the energy in a temperature range from 100 K to 823 K.

关键词： biaxial strain phonon band gap GaN