Al,Ca,and Zn are representative commercial alloying elements for Mg alloys.To investigate the effects of these elements on the deformation and recrystallization behaviors of Mg alloys,we develop interatomic potentials...Al,Ca,and Zn are representative commercial alloying elements for Mg alloys.To investigate the effects of these elements on the deformation and recrystallization behaviors of Mg alloys,we develop interatomic potentials for the Al-Ca,Al-Zn,Mg-Al-Ca and Mg-Al-Zn systems based on the second nearest-neighbor modified embedded-atom method formalism.The developed potentials describe structural,elastic,and thermodynamic properties of compounds and solutions of associated alloy systems in reasonable agreement with experimental data and higher-level calculations.The applicability of these potentials to the present investigation is confirmed by calculating the generalized stacking fault energy for various slip systems and the segregation energy on twin boundaries of the Mg-Al-Ca and Mg-Al-Zn alloys,accompanied with the thermal expansion coefficient and crystal structure maintenance of stable compounds in those alloys.展开更多
In this paper, we deduce the analytical form of many-body interatomic potentials based on the Green’s function in tight-binding representation. The many-body potentials are expressed as the functions of the hopping i...In this paper, we deduce the analytical form of many-body interatomic potentials based on the Green’s function in tight-binding representation. The many-body potentials are expressed as the functions of the hopping integrals which are the physical origin of cohesion of atoms. For thesimple case of s-valent system, the inversion of the many-body potentials are discussed in detail by using the lattice inversion method.展开更多
The cleavage force F(z) needed to separate parallel atomic planes by a distance z is first discussed for simple s-p metals using density functional theory.For the s-p nearly free-electron metals the linearized Thomas-...The cleavage force F(z) needed to separate parallel atomic planes by a distance z is first discussed for simple s-p metals using density functional theory.For the s-p nearly free-electron metals the linearized Thomas-Fermi equation is solved self-consistently in the cases of (a) semi-infinite planes of jellium (i.e. smeared uniform positive ions) and (b) a semi-infinite cylinder of finite radius, cleaved by a plane perpendicular to its axis. In (a), the elastic region has the form F(z)=Az ∝ Zrs-11/2, where rs is the mean interelectronic distance in the jellium model. Size effects are then considered, with possible relevance to atomic force microscopy.Defect energies are treated, using both electron theory and pair force laws.展开更多
We applied an approach to the development of many-body interatomic potentials for NiZr alloys,gaining an improved accuracy and reliability.The functional form of the potential is that of the embedded method,but it has...We applied an approach to the development of many-body interatomic potentials for NiZr alloys,gaining an improved accuracy and reliability.The functional form of the potential is that of the embedded method,but it has been improved as follows. (1) The database used for the development of the potential includes both experimental data and a large set of energies of different structures of the alloys generated by Fab initio calculations. (2) The optimum parametrization of the potential for the given database is obtained by fitting. Using this approach we developed reliable interatomic potentials for Ni and Zr. The potential accurately reproduces basic equilibrium properties of the alloys.展开更多
In this paper, a mathematical relation was found between interatomic Hooke’s force constant and both the bulk modulus and interatomic distance in solid crystals, considering that the forces which have effect on an at...In this paper, a mathematical relation was found between interatomic Hooke’s force constant and both the bulk modulus and interatomic distance in solid crystals, considering that the forces which have effect on an atom are only those resulted from the neighboring atoms, and the forces are subject to Hooke’s law as the deflections of atoms from their equilibrium positions are very small. This work has been applied on some solid semiconducting crystals of diatomic primitive cell, including crystals of mono-atomic primitive cell automatically, by using linear statistical fitting with computer programming and, then, using mathematical analysis, proceeding from the vibrational dispersion relation of solid linear lattice, these two methods have been used in the process in order to support each other and for the result to be satisfying and reasonable. This is a contribution to the process of using computer programming in physics to facilitate mathematical analyses and obtain the required relations and functions by designing and developing appropriate computer programs in line with the macro and micro natures of materials. The importance of this is in enhancing our understanding of the interatomic actions in cells and of the crystal structure of materials in general and semiconductors in particular, as it is a step of the initial steps to facilitate the process of calculating energies and extracting mathematical relations between correlation energy and temperature as well as between sub-fusion and fusion energies with temperature.展开更多
Motivated by the special theory of gradient elasticity (GradEla), a proposal is advanced for extending it to construct gradient models for interatomic potentials, commonly used in atomistic simulations. Our focus is o...Motivated by the special theory of gradient elasticity (GradEla), a proposal is advanced for extending it to construct gradient models for interatomic potentials, commonly used in atomistic simulations. Our focus is on London’s quantum mechanical potential which is an analytical expression valid until a certain characteristic distance where “attractive” molecular interactions change character and become “repulsive” and cannot be described by the classical form of London’s potential. It turns out that the suggested internal length gradient (ILG) generalization of London’s potential generates both an “attractive” and a “repulsive” branch, and by adjusting the corresponding gradient parameters, the behavior of the empirical Lennard-Jones potentials is theoretically captured.展开更多
It is shown that electrons forming simple and multiple covalent bonds may have different contribu-tions to the interatomic interactions due to the degeneracy of electron states. A simple relationship between the lengt...It is shown that electrons forming simple and multiple covalent bonds may have different contribu-tions to the interatomic interactions due to the degeneracy of electron states. A simple relationship between the length of covalent bond, its order and atomic numbers of the interacting atoms is de-duced.展开更多
Experimental results of the temperature dependence of critical resolved. shear stresses (CRSS)of Mo, Fe, Al and Mg single crystals are shown. Associating reports in recent years, we point out that the approximate expo...Experimental results of the temperature dependence of critical resolved. shear stresses (CRSS)of Mo, Fe, Al and Mg single crystals are shown. Associating reports in recent years, we point out that the approximate exponential relationship between CRSS and the absolute temperatureat least in the region of the steep temperature dependence range of many materials is more common, even for bcc, fcc, and hcp single crystals. polycrystals and other covalent crystals,provided that the slip plane and slip direction are kept the same. Successful explanation with atomic force law shows that the interatomic forces (electronic structure) play a decisive role in determining the temperature dependence of yield stresses for a large number of materials.展开更多
A model of binding forces in metals and alloys, based on the density functional theory and accounted effects of the many-body interactions, was proposed. The developed method can be easily applied for study of metals ...A model of binding forces in metals and alloys, based on the density functional theory and accounted effects of the many-body interactions, was proposed. The developed method can be easily applied for study of metals and alloys by the molecular dynamics simulation. The potentials of interatomic interactions have been found by the proposed method and applied for calculations of equation of state, elastic moduli and phonon dispersion in metals Ni, Al, alloys NiAl and Ni3Al. Results of the calculations are in good agreement with known experimental data both for pure metals and alloys.展开更多
Diatomic site catalysts(DACs)with two adjacent atomic metal species can provide synergistic interactions and more sophisticated functionalities to break the bottleneck of intrinsic drawbacks of single atom catalysts(S...Diatomic site catalysts(DACs)with two adjacent atomic metal species can provide synergistic interactions and more sophisticated functionalities to break the bottleneck of intrinsic drawbacks of single atom catalysts(SACs).Herein,we have designed a CuZn diatomic site(CuZn-DAS)electrocatalyst with unique coordination structure(CuN_(4)-ZnN_(4))by anchoring and ordering the spatial distance between the metal precursors on the carbon nitride(C_(3)N_(4))derived N-doped carbon(NC)substrate.The CuZn-DAS/NC shows high activity and selectivity for electroreduction CO_(2)into CO.The Faradaic efficiency for CO of CuZn-DAS/NC(98.4%)is higher than that of Cu single atomic site on NC(Cu-SAS/NC)(36.4%)and Zn single atomic site on NC(Zn-SAS/NC)(66.8%)at-0.6 V versus reversible hydrogen electrode(vs.RHE).In situ characterizations reveal that the CuZn-DAS is more favorable for the formation and adsorption of^(*)COOH than those of the electrocatalysts with single atomic site.Theorical calculations show that the charge redistribution of Zn site in CuZn-DAS/NC caused by the considerable electron transfers from Zn atoms to the adjacent Cu atoms can reduce the adsorption energy barriers for^(*)COOH and^(*)CO production,improving the activity and CO selectivity.展开更多
The structure and properties of materials under neutron irradiation are an important basis in future fusion reactors.In the absence of fusion neutron sources for irradiation experiments,it is increasingly important an...The structure and properties of materials under neutron irradiation are an important basis in future fusion reactors.In the absence of fusion neutron sources for irradiation experiments,it is increasingly important and urgent to carry out neutron irradiation simulations on fusion reactor materials and then establish complete databases of defect properties and collisional cascades,where the first and foremost step is to select suitable interatomic potentials for atomistic-level simulations.In this work,six typic interatomic potentials for tungsten(W)are evaluated and reviewed systematically for radiation damage simulations.The relative lattice stability and elastic constants of bulk W are considered first with those potentials;then,the properties of point defects and defect clusters at interstitial sites and vacancies are obtained by molecular statics/dynam-ics simulations.The formation energies of interstitial/vacancy clusters,1/2<111>and<100>dislocation loops in W and the threshold displacement energies along different directions are also determined.In addition,the extended defects are further investigated,such as free surfaces and the energy profiles of 1/2<111>{110}and 1/2<111>{112}stacking faults.The current results provide a reference for selecting W potentials to simulate the radiation damage.展开更多
The potential functions of the F-S model for ordered high-temperature intermetallic compound NiAl with a B2 structure are constructed by fitting the lattice constant,cohesive energy and the bulk modulus.And by using t...The potential functions of the F-S model for ordered high-temperature intermetallic compound NiAl with a B2 structure are constructed by fitting the lattice constant,cohesive energy and the bulk modulus.And by using the pressure-volume (P-V) relation proposed by Rose et al,the potential functions are modified further.Based on the potentials and also for a testing of the potentials,the point defects properties have been studied by the molecular dynamics method.展开更多
Carbon neutrality has been proposed as a solution for the current severe energy and climate crisis caused by the overuse of fossil fuels, and machine learning(ML) has exhibited excellent performance in accelerating re...Carbon neutrality has been proposed as a solution for the current severe energy and climate crisis caused by the overuse of fossil fuels, and machine learning(ML) has exhibited excellent performance in accelerating related research owing to its powerful capacity for big data processing. This review presents a detailed overview of ML accelerated carbon neutrality research with a focus on energy management, screening of novel energy materials, and ML interatomic potentials(MLIPs), with illustrations of two selected MLIP algorithms: moment tensor potential(MTP) and neural equivariant interatomic potential(NequIP). We conclude by outlining the important role of ML in accelerating the achievement of carbon neutrality from global-scale energy management, unprecedented screening of advanced energy materials in massive chemical space, to the revolution of atomicscale simulations of MLIPs, which has the bright prospect of applications.展开更多
We present a method to model interatomic interactions such as energy and forces in a computationally efficient way.The proposed model approximates the energy/forces using a linear combination of random features,thereb...We present a method to model interatomic interactions such as energy and forces in a computationally efficient way.The proposed model approximates the energy/forces using a linear combination of random features,thereby enabling fast parameter estimation by solving a linear least-squares problem.We discuss how random features based on stationary and non-stationary kernels can be used for energy approximation and provide results for three classes of materials,namely two-dimensional materials,metals and semiconductors.Force and energy predictions made using the proposed method are in close agreement with density functional theory calculations,with training time that is 96%lower than standard kernel models.Molecular Dynamics calculations using random features based interatomic potentials are shown to agree well with experimental and density functional theory values.Phonon frequencies as computed by random features based interatomic potentials are within 0.1%of the density functional theory results.Furthermore,the proposed random features-based potential addresses scalability issues encountered in this class of machine learning problems.展开更多
This paper summarizes the progress of machine-learning-based interatomic potentials and their applications in advanced manufacturing.Interatomic potential is essential for classical molecular dynamics.The advancements...This paper summarizes the progress of machine-learning-based interatomic potentials and their applications in advanced manufacturing.Interatomic potential is essential for classical molecular dynamics.The advancements made in machine learning(ML)have enabled the development of fast interatomic potential with ab initio accuracy.The accelerated atomic simulation can greatly transform the design principle of manufacturing technology.The most widely used supervised and unsupervised ML methods are summarized and compared.Then,the emerging interatomic models based on ML are discussed:Gaussian approximation potential,spectral neighbor analysis potential,deep potential molecular dynamics,SCHNET,hierarchically interacting particle neural network,and fast learning of atomistic rare events.展开更多
To shed a light on Xe bubble nucleation in U–Mo fuel from the view of primary irradiation damage,a reported U–Mo–Xe potential under the framework of embedded atom method has been modified within the range of short ...To shed a light on Xe bubble nucleation in U–Mo fuel from the view of primary irradiation damage,a reported U–Mo–Xe potential under the framework of embedded atom method has been modified within the range of short and intermediate atomic distance.The modified potential can better describe the interactions between energetic particles,and can accurately reproduce the threshold displacement energy surface calculated by the first-principles method.Then,molecular dynamics simulations of primary irradiation damage in U–Mo–Xe system have been conducted under different contents.The raise of Xe concentration brings about a remarkable promotion in residual defect quantity and generates bubbles in more overpressured state,which suggests an acceleration of irradiation damage under the accumulation of the fission gas.Meanwhile,the addition of Mo considerably reduces the residual defect count and hinders irradiation-induced Xe diffusion especially at high contents of Xe,corroborating the importance of high Mo content in mitigation of irradiation damage and swelling behavior in U–Mo fuel.In particular,the variation of irradiation damage with respect to contents suggests a necessity of taking into account the influence of local components on defect evolution in mesoscale simulations.展开更多
The investigation of thermal transport is crucial to the thermal management of modern electronic devices.To obtain the thermal conductivity through solution of the Boltzmann transport equation,calculation of the anhar...The investigation of thermal transport is crucial to the thermal management of modern electronic devices.To obtain the thermal conductivity through solution of the Boltzmann transport equation,calculation of the anharmonic interatomic force constants has a high computational cost based on the current method of single-point density functional theory force calculation.The recent suggested machine learning interatomic potentials(MLIPs)method can avoid these huge computational demands.In this work,we study the thermal conductivity of two-dimensional MoS_(2)-like hexagonal boron dichalcogenides(H-B_(2)VI_(2);V I=S,Se,Te)with a combination of MLIPs and the phonon Boltzmann transport equation.The room-temperature thermal conductivity of H-B_(2)S_(2)can reach up to 336 W·m^(-1)·K^(-1),obviously larger than that of H-B_(2)Se_(2)and H-B_(2)Te_(2).This is mainly due to the difference in phonon group velocity.By substituting the different chalcogen elements in the second sublayer,H-B_(2)VIV I′have lower thermal conductivity than H-B_(2)VI_(2).The room-temperature thermal conductivity of B2STe is only 11%of that of H-B_(2)S_(2).This can be explained by comparing phonon group velocity and phonon relaxation time.The MLIP method is proved to be an efficient method for studying the thermal conductivity of materials,and H-B_(2)S_(2)-based nanodevices have excellent thermal conduction.展开更多
We have recently proposed a nanoscale continuum theory for carbonnanotubes.The theory links continuum analysis with atomistic modeling by incor-porating interatomic potentials and atomic structures of carbon nanotubes...We have recently proposed a nanoscale continuum theory for carbonnanotubes.The theory links continuum analysis with atomistic modeling by incor-porating interatomic potentials and atomic structures of carbon nanotubes directlyinto the constitutive law.Here we address two main issues involved in setting upthe nanoscale continuum theory for carbon nanotubes,namely the multi-body in-teratomic potentials and the lack of centrosymmetry in the nanotube structure.Weexplain the key ideas behind these issues in establishing a nanoscale continuum theoryin terms of interatomic potentials and atomic structures.展开更多
INTRODUCTIONIn the deyelopment of material science,it 15 desirable that theand elastic eonstants whieh are the imPoaceurately calculated by means ofrtant meehanical ProPertieseohesive energiesof erystals ean bePhysiea...INTRODUCTIONIn the deyelopment of material science,it 15 desirable that theand elastic eonstants whieh are the imPoaceurately calculated by means ofrtant meehanical ProPertieseohesive energiesof erystals ean bePhysieal meehanies method .展开更多
To reveal the potential aging mechanism for self-irradiation in Pu-Ga alloy,we choose Au-Ag alloy as its substitutional material in terms of its mass density and lattice structure.As a first step for understanding the...To reveal the potential aging mechanism for self-irradiation in Pu-Ga alloy,we choose Au-Ag alloy as its substitutional material in terms of its mass density and lattice structure.As a first step for understanding the microscopic behavior of point defects in Au-Ag alloy,we perform a molecular dynamics(MD)simulation on energetics and diffusion of point defects in Au and Ag metal.Our results indicate that the octahedral self-interstitial atom(SIA)is more stable than the tetrahedral SIA.The stability sequence of point defects for He atom in Au/Ag is:substitutional site>octahedral interstitial site>tetrahedral interstitial site.The He-V cluster(Hen Vm,V denotes vacancy)is the most stable at n=m.For the mono-vacancy diffusion,the MD calculation shows that the first nearest neighbour(1 NN)site is the most favorable site on the basis of the nudged elastic band(NEB)calculation,which is in agreement with previous experimental data.There are two peaks for the second nearest neighbour(2 NN)and the third nearest neighbour(3 NN)diffusion curve in octahedral interstitial site for He atom,indicating that the 2 NN and 3 NN diffusion for octahedral SIA would undergo an intermediate defect structure similar to the 1 NN site.The 3 NN diffusion for the tetrahedral SIA and He atom would undergo an intermediate site in analogy to its initial structure.For diffusion of point defects,the vacancy,SIA,He atom and He-V cluster may have an analogous effect on the diffusion velocity in Ag.展开更多
文摘Al,Ca,and Zn are representative commercial alloying elements for Mg alloys.To investigate the effects of these elements on the deformation and recrystallization behaviors of Mg alloys,we develop interatomic potentials for the Al-Ca,Al-Zn,Mg-Al-Ca and Mg-Al-Zn systems based on the second nearest-neighbor modified embedded-atom method formalism.The developed potentials describe structural,elastic,and thermodynamic properties of compounds and solutions of associated alloy systems in reasonable agreement with experimental data and higher-level calculations.The applicability of these potentials to the present investigation is confirmed by calculating the generalized stacking fault energy for various slip systems and the segregation energy on twin boundaries of the Mg-Al-Ca and Mg-Al-Zn alloys,accompanied with the thermal expansion coefficient and crystal structure maintenance of stable compounds in those alloys.
文摘In this paper, we deduce the analytical form of many-body interatomic potentials based on the Green’s function in tight-binding representation. The many-body potentials are expressed as the functions of the hopping integrals which are the physical origin of cohesion of atoms. For thesimple case of s-valent system, the inversion of the many-body potentials are discussed in detail by using the lattice inversion method.
文摘The cleavage force F(z) needed to separate parallel atomic planes by a distance z is first discussed for simple s-p metals using density functional theory.For the s-p nearly free-electron metals the linearized Thomas-Fermi equation is solved self-consistently in the cases of (a) semi-infinite planes of jellium (i.e. smeared uniform positive ions) and (b) a semi-infinite cylinder of finite radius, cleaved by a plane perpendicular to its axis. In (a), the elastic region has the form F(z)=Az ∝ Zrs-11/2, where rs is the mean interelectronic distance in the jellium model. Size effects are then considered, with possible relevance to atomic force microscopy.Defect energies are treated, using both electron theory and pair force laws.
基金Supported by the National Natural Science Foundation of China(No.2 9892 16 6 ,2 980 30 0 6 ,2 99830 0 1)
文摘We applied an approach to the development of many-body interatomic potentials for NiZr alloys,gaining an improved accuracy and reliability.The functional form of the potential is that of the embedded method,but it has been improved as follows. (1) The database used for the development of the potential includes both experimental data and a large set of energies of different structures of the alloys generated by Fab initio calculations. (2) The optimum parametrization of the potential for the given database is obtained by fitting. Using this approach we developed reliable interatomic potentials for Ni and Zr. The potential accurately reproduces basic equilibrium properties of the alloys.
文摘In this paper, a mathematical relation was found between interatomic Hooke’s force constant and both the bulk modulus and interatomic distance in solid crystals, considering that the forces which have effect on an atom are only those resulted from the neighboring atoms, and the forces are subject to Hooke’s law as the deflections of atoms from their equilibrium positions are very small. This work has been applied on some solid semiconducting crystals of diatomic primitive cell, including crystals of mono-atomic primitive cell automatically, by using linear statistical fitting with computer programming and, then, using mathematical analysis, proceeding from the vibrational dispersion relation of solid linear lattice, these two methods have been used in the process in order to support each other and for the result to be satisfying and reasonable. This is a contribution to the process of using computer programming in physics to facilitate mathematical analyses and obtain the required relations and functions by designing and developing appropriate computer programs in line with the macro and micro natures of materials. The importance of this is in enhancing our understanding of the interatomic actions in cells and of the crystal structure of materials in general and semiconductors in particular, as it is a step of the initial steps to facilitate the process of calculating energies and extracting mathematical relations between correlation energy and temperature as well as between sub-fusion and fusion energies with temperature.
文摘Motivated by the special theory of gradient elasticity (GradEla), a proposal is advanced for extending it to construct gradient models for interatomic potentials, commonly used in atomistic simulations. Our focus is on London’s quantum mechanical potential which is an analytical expression valid until a certain characteristic distance where “attractive” molecular interactions change character and become “repulsive” and cannot be described by the classical form of London’s potential. It turns out that the suggested internal length gradient (ILG) generalization of London’s potential generates both an “attractive” and a “repulsive” branch, and by adjusting the corresponding gradient parameters, the behavior of the empirical Lennard-Jones potentials is theoretically captured.
文摘It is shown that electrons forming simple and multiple covalent bonds may have different contribu-tions to the interatomic interactions due to the degeneracy of electron states. A simple relationship between the length of covalent bond, its order and atomic numbers of the interacting atoms is de-duced.
文摘Experimental results of the temperature dependence of critical resolved. shear stresses (CRSS)of Mo, Fe, Al and Mg single crystals are shown. Associating reports in recent years, we point out that the approximate exponential relationship between CRSS and the absolute temperatureat least in the region of the steep temperature dependence range of many materials is more common, even for bcc, fcc, and hcp single crystals. polycrystals and other covalent crystals,provided that the slip plane and slip direction are kept the same. Successful explanation with atomic force law shows that the interatomic forces (electronic structure) play a decisive role in determining the temperature dependence of yield stresses for a large number of materials.
文摘A model of binding forces in metals and alloys, based on the density functional theory and accounted effects of the many-body interactions, was proposed. The developed method can be easily applied for study of metals and alloys by the molecular dynamics simulation. The potentials of interatomic interactions have been found by the proposed method and applied for calculations of equation of state, elastic moduli and phonon dispersion in metals Ni, Al, alloys NiAl and Ni3Al. Results of the calculations are in good agreement with known experimental data both for pure metals and alloys.
基金This study was supported by the National Natural Science Foundation of China(Nos.52073124 and 52273058)the Natural Science Foundation of Jiangsu Province(No.SBK2022030167)+1 种基金the MOE&SAFEA,111 Project(No.B13025)the Fundamental Research Funds for the Central Universities.
文摘Diatomic site catalysts(DACs)with two adjacent atomic metal species can provide synergistic interactions and more sophisticated functionalities to break the bottleneck of intrinsic drawbacks of single atom catalysts(SACs).Herein,we have designed a CuZn diatomic site(CuZn-DAS)electrocatalyst with unique coordination structure(CuN_(4)-ZnN_(4))by anchoring and ordering the spatial distance between the metal precursors on the carbon nitride(C_(3)N_(4))derived N-doped carbon(NC)substrate.The CuZn-DAS/NC shows high activity and selectivity for electroreduction CO_(2)into CO.The Faradaic efficiency for CO of CuZn-DAS/NC(98.4%)is higher than that of Cu single atomic site on NC(Cu-SAS/NC)(36.4%)and Zn single atomic site on NC(Zn-SAS/NC)(66.8%)at-0.6 V versus reversible hydrogen electrode(vs.RHE).In situ characterizations reveal that the CuZn-DAS is more favorable for the formation and adsorption of^(*)COOH than those of the electrocatalysts with single atomic site.Theorical calculations show that the charge redistribution of Zn site in CuZn-DAS/NC caused by the considerable electron transfers from Zn atoms to the adjacent Cu atoms can reduce the adsorption energy barriers for^(*)COOH and^(*)CO production,improving the activity and CO selectivity.
基金This work was financially supported by the National MCF Energy R&D Program of China(Grant No.2018YFE0308101)the National Key R&D Program of China(Grant No.2018YFB0704002)the National Natural Science Foundation of China(Grant Nos.51771073,11975260).
文摘The structure and properties of materials under neutron irradiation are an important basis in future fusion reactors.In the absence of fusion neutron sources for irradiation experiments,it is increasingly important and urgent to carry out neutron irradiation simulations on fusion reactor materials and then establish complete databases of defect properties and collisional cascades,where the first and foremost step is to select suitable interatomic potentials for atomistic-level simulations.In this work,six typic interatomic potentials for tungsten(W)are evaluated and reviewed systematically for radiation damage simulations.The relative lattice stability and elastic constants of bulk W are considered first with those potentials;then,the properties of point defects and defect clusters at interstitial sites and vacancies are obtained by molecular statics/dynam-ics simulations.The formation energies of interstitial/vacancy clusters,1/2<111>and<100>dislocation loops in W and the threshold displacement energies along different directions are also determined.In addition,the extended defects are further investigated,such as free surfaces and the energy profiles of 1/2<111>{110}and 1/2<111>{112}stacking faults.The current results provide a reference for selecting W potentials to simulate the radiation damage.
基金Project supported by the National Natural Science Foundation of China.
文摘The potential functions of the F-S model for ordered high-temperature intermetallic compound NiAl with a B2 structure are constructed by fitting the lattice constant,cohesive energy and the bulk modulus.And by using the pressure-volume (P-V) relation proposed by Rose et al,the potential functions are modified further.Based on the potentials and also for a testing of the potentials,the point defects properties have been studied by the molecular dynamics method.
基金supported by the National Natural Science Foundation of China (Grant No. 52173234)the Shenzhen Science and Technology Program (Grant Nos. JCYJ20210324102008023 and JSGG202108021534-08024)+3 种基金the Shenzhen-Hong Kong-Macao Technology Research Program(Type C, SGDX2020110309300301)the Natural Science Foundation of Guangdong Province (Grant No. 2022A1515010554)CCF-Tencent Open FundNingbo Municipal Key Laboratory on Clean Energy Conversion Technologies and the Zhejiang Provincial Key Laboratory for Carbonaceous Wastes Processing and Process Intensification Research funded by the Zhejiang Provincial Department of Science and Technology (Grant No. 2020E10018)
文摘Carbon neutrality has been proposed as a solution for the current severe energy and climate crisis caused by the overuse of fossil fuels, and machine learning(ML) has exhibited excellent performance in accelerating related research owing to its powerful capacity for big data processing. This review presents a detailed overview of ML accelerated carbon neutrality research with a focus on energy management, screening of novel energy materials, and ML interatomic potentials(MLIPs), with illustrations of two selected MLIP algorithms: moment tensor potential(MTP) and neural equivariant interatomic potential(NequIP). We conclude by outlining the important role of ML in accelerating the achievement of carbon neutrality from global-scale energy management, unprecedented screening of advanced energy materials in massive chemical space, to the revolution of atomicscale simulations of MLIPs, which has the bright prospect of applications.
基金This research is supported by grants from Natural Sciences and Engineering Research Council of Canada,Hart Professorship,Canada Research Chairs programme,the University of Toronto,and Compute Canada.
文摘We present a method to model interatomic interactions such as energy and forces in a computationally efficient way.The proposed model approximates the energy/forces using a linear combination of random features,thereby enabling fast parameter estimation by solving a linear least-squares problem.We discuss how random features based on stationary and non-stationary kernels can be used for energy approximation and provide results for three classes of materials,namely two-dimensional materials,metals and semiconductors.Force and energy predictions made using the proposed method are in close agreement with density functional theory calculations,with training time that is 96%lower than standard kernel models.Molecular Dynamics calculations using random features based interatomic potentials are shown to agree well with experimental and density functional theory values.Phonon frequencies as computed by random features based interatomic potentials are within 0.1%of the density functional theory results.Furthermore,the proposed random features-based potential addresses scalability issues encountered in this class of machine learning problems.
基金This study was supported by the Wuhan University Junior Faculty Research(2042019KF0003)the National Natural Science Foundation of China(51727901,U1501241,and 62174122)+1 种基金the National Key R&D Program of China(2017YFB1103904)the Hubei Provincial Natural Science Foundation of China(2020CFA032).
文摘This paper summarizes the progress of machine-learning-based interatomic potentials and their applications in advanced manufacturing.Interatomic potential is essential for classical molecular dynamics.The advancements made in machine learning(ML)have enabled the development of fast interatomic potential with ab initio accuracy.The accelerated atomic simulation can greatly transform the design principle of manufacturing technology.The most widely used supervised and unsupervised ML methods are summarized and compared.Then,the emerging interatomic models based on ML are discussed:Gaussian approximation potential,spectral neighbor analysis potential,deep potential molecular dynamics,SCHNET,hierarchically interacting particle neural network,and fast learning of atomistic rare events.
基金the National Key Research and Development Program of China(Grant No.2017YFB0702401)the National Natural Science Foundation of China(Grant No.51631005).
文摘To shed a light on Xe bubble nucleation in U–Mo fuel from the view of primary irradiation damage,a reported U–Mo–Xe potential under the framework of embedded atom method has been modified within the range of short and intermediate atomic distance.The modified potential can better describe the interactions between energetic particles,and can accurately reproduce the threshold displacement energy surface calculated by the first-principles method.Then,molecular dynamics simulations of primary irradiation damage in U–Mo–Xe system have been conducted under different contents.The raise of Xe concentration brings about a remarkable promotion in residual defect quantity and generates bubbles in more overpressured state,which suggests an acceleration of irradiation damage under the accumulation of the fission gas.Meanwhile,the addition of Mo considerably reduces the residual defect count and hinders irradiation-induced Xe diffusion especially at high contents of Xe,corroborating the importance of high Mo content in mitigation of irradiation damage and swelling behavior in U–Mo fuel.In particular,the variation of irradiation damage with respect to contents suggests a necessity of taking into account the influence of local components on defect evolution in mesoscale simulations.
基金Scientific and Technological Research of Chongqing Municipal Education Commission(Grant No.KJZD-K202100602)the funding of Institute for Advanced Sciences of Chongqing University of Posts and Telecommunications(Grant No.E011A2022326)。
文摘The investigation of thermal transport is crucial to the thermal management of modern electronic devices.To obtain the thermal conductivity through solution of the Boltzmann transport equation,calculation of the anharmonic interatomic force constants has a high computational cost based on the current method of single-point density functional theory force calculation.The recent suggested machine learning interatomic potentials(MLIPs)method can avoid these huge computational demands.In this work,we study the thermal conductivity of two-dimensional MoS_(2)-like hexagonal boron dichalcogenides(H-B_(2)VI_(2);V I=S,Se,Te)with a combination of MLIPs and the phonon Boltzmann transport equation.The room-temperature thermal conductivity of H-B_(2)S_(2)can reach up to 336 W·m^(-1)·K^(-1),obviously larger than that of H-B_(2)Se_(2)and H-B_(2)Te_(2).This is mainly due to the difference in phonon group velocity.By substituting the different chalcogen elements in the second sublayer,H-B_(2)VIV I′have lower thermal conductivity than H-B_(2)VI_(2).The room-temperature thermal conductivity of B2STe is only 11%of that of H-B_(2)S_(2).This can be explained by comparing phonon group velocity and phonon relaxation time.The MLIP method is proved to be an efficient method for studying the thermal conductivity of materials,and H-B_(2)S_(2)-based nanodevices have excellent thermal conduction.
文摘We have recently proposed a nanoscale continuum theory for carbonnanotubes.The theory links continuum analysis with atomistic modeling by incor-porating interatomic potentials and atomic structures of carbon nanotubes directlyinto the constitutive law.Here we address two main issues involved in setting upthe nanoscale continuum theory for carbon nanotubes,namely the multi-body in-teratomic potentials and the lack of centrosymmetry in the nanotube structure.Weexplain the key ideas behind these issues in establishing a nanoscale continuum theoryin terms of interatomic potentials and atomic structures.
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基金Project supported by the National Natural Science Foundation of China(Grant Nos.51401237,11474358,and 51271198)the Fund from Shaanxi Provincial Education Department,China(Grant No.18JK1207)the Defence Technology Foundation of China(Grant No.2301003)
文摘To reveal the potential aging mechanism for self-irradiation in Pu-Ga alloy,we choose Au-Ag alloy as its substitutional material in terms of its mass density and lattice structure.As a first step for understanding the microscopic behavior of point defects in Au-Ag alloy,we perform a molecular dynamics(MD)simulation on energetics and diffusion of point defects in Au and Ag metal.Our results indicate that the octahedral self-interstitial atom(SIA)is more stable than the tetrahedral SIA.The stability sequence of point defects for He atom in Au/Ag is:substitutional site>octahedral interstitial site>tetrahedral interstitial site.The He-V cluster(Hen Vm,V denotes vacancy)is the most stable at n=m.For the mono-vacancy diffusion,the MD calculation shows that the first nearest neighbour(1 NN)site is the most favorable site on the basis of the nudged elastic band(NEB)calculation,which is in agreement with previous experimental data.There are two peaks for the second nearest neighbour(2 NN)and the third nearest neighbour(3 NN)diffusion curve in octahedral interstitial site for He atom,indicating that the 2 NN and 3 NN diffusion for octahedral SIA would undergo an intermediate defect structure similar to the 1 NN site.The 3 NN diffusion for the tetrahedral SIA and He atom would undergo an intermediate site in analogy to its initial structure.For diffusion of point defects,the vacancy,SIA,He atom and He-V cluster may have an analogous effect on the diffusion velocity in Ag.
