Batteries play a critical role in electric vehicles and distributed energy generation.With the growing demand for energy storage solutions,new battery materials and systems are continually being developed.In this proc...Batteries play a critical role in electric vehicles and distributed energy generation.With the growing demand for energy storage solutions,new battery materials and systems are continually being developed.In this process,molecular dynamics(MD)simulations can reveal the microscopic mechanisms of battery processes,thereby boosting the design of batteries.Compared to other MD simulation techniques,the machine learning force field(MLFF)holds the advantages of first-principles accuracy along with large spatial and temporal scale,offering opportunities to uncover new mechanisms in battery systems.This review presents a detailed overview of the fundamental principles and model types of MLFFs,as well as their applications in simulating the structure,transport properties,and chemical reaction properties of bulk battery materials and interfaces.Notably,we emphasize the long-range interaction corrections and constant-potential methods in the model design of MLFFs.Finally,we discuss the challenges and prospects of applying MLFF models in the research of batteries.展开更多
The interstellar medium molecule thiocarbonyl thioketen,H_(2)CCS,has several stable isomers and has received considerable attention of as-tronomical observation in recent years.The positions of H,C,and S atoms of thre...The interstellar medium molecule thiocarbonyl thioketen,H_(2)CCS,has several stable isomers and has received considerable attention of as-tronomical observation in recent years.The positions of H,C,and S atoms of three isomers lead to di-verse dipole moments and spectro-scopic constants.The anharmonic force field and spectroscopic con-stants of thiocarbonyl thioketen and its isomers are calculated using MP2,B3LYP,and CCSD(T)methods employing correlation consistent basis sets.Molecule structures,rotational spectroscopic constants,and fundamental frequencies are compared with the available experimental data for thiocarbonyl thioketen.Ro-vibrational interaction constants,anharmonic constants,cubic and quartic force constants are predicted for thiocarbonyl thioketen.In addition,some rotational and vibrational spectroscopic parameters are predict-ed with the same level of theory for thioacetylene,HCCSH,and thiirene,(CH)_(2)S.The predic-tions of these spectroscopic constants are expected to guide the future astronomical observa-tion and high resolution experimental work for C_(2)H_(2)S isomers.展开更多
Bimetallic surfaces play a pivotal role in heterogeneous catalysis,yet their theoretical modeling has long been hindered by the computational chal-lenges of capturing configurational disorder,a critical feature govern...Bimetallic surfaces play a pivotal role in heterogeneous catalysis,yet their theoretical modeling has long been hindered by the computational chal-lenges of capturing configurational disorder,a critical feature governing their catalytic properties.Tradition-al approaches rely on oversimplified ordered surface models or restrict dis-order to a few atomic layers,limiting their predictive power.Here,we Cu_(1-x)Zn_(x)Cu_(1-x)Zn_(x)present an accurate and efficient computational framework that integrates machine learning force fields(MLFFs)with the cluster expansion(CE)method to study configurationally dis-ordered bimetallic surfaces at finite temperatures.We have developed an efficient workflow in which the MLFF is first trained iteratively via an active learning protocol,and then used to generate accurate energetic data for thousands of configurations that enable robust CE model construction.By treating bulk and surface clusters separately,we can build CE models for surface slabs with an arbitrary number of layers.Using as a case study,our CE-based Monte Carlo simulations reveal key structural insights that are relevant to the under-standing of catalytic properties of surfaces.This work demonstrates how MLFF-aided CE can overcome traditional limitations in theoretical modeling of bimetallic surfaces and highlights pathways toward more realistic modeling of heterogeneous catalysts.展开更多
Large-scale molecular dynamics(MD) simulations of crosslinked epoxy with quantum-level accuracy while capturing complex reactivity is a compelling yet unrealized challenge. In this work, through the construction of a ...Large-scale molecular dynamics(MD) simulations of crosslinked epoxy with quantum-level accuracy while capturing complex reactivity is a compelling yet unrealized challenge. In this work, through the construction of a chemical-environment-directing dataset, a reactive machine learning force field that accurately captures both reactive events and thermos-mechanical properties is developed. The force field achieves energy and force root-mean-square errors of 1.3 meV/atom and 159 meV/A, respectively, and operates approximately 1200 times faster than ab initio molecular dynamics. MD simulations demonstrate excellent predictive capabilities across multiple critical thermos-mechanical properties(radial distribution function, density, and elastic modulus), with results being well consistent with experimental values. In particular, the force field can provide accurate prediction of the bond dissociation energies for typical bonds with a mean absolute error of 7.8 kcal/mol(<8%), which enables the simulation of tensile-induced failure caused by chemical bond breaking. Our work demonstrates the capability of the machine learning force field to handle the extraordinary complexity of crosslinked epoxy systems, providing a valuable blueprint for future development of more generalized reactive force fields applicable to most polymers.展开更多
Levitated optomechanical systems represent an excellent candidate platform for force and acceleration sensing.We propose a force-sensing protocol utilizing an optically levitated nanoparticle array.In our scheme,N nan...Levitated optomechanical systems represent an excellent candidate platform for force and acceleration sensing.We propose a force-sensing protocol utilizing an optically levitated nanoparticle array.In our scheme,N nanoparticles are trapped in an optical cavity using holographic optical tweezers.An external laser drives the cavity,exciting N cavity modes interacting simultaneously with the N nanoparticles.The optomechanical interaction encodes the information of the force acting on each nanoparticle onto the intracavity photons,which can be detected directly at the output ports of the cavity.Consequently,our protocol enables real-time imaging of a force field.展开更多
In modern processing of conducting materials, such as steel,the time-varying electromagnetic field plays a key role in obtaining the desired microstructure or eliminating solidification defects such as porosity and se...In modern processing of conducting materials, such as steel,the time-varying electromagnetic field plays a key role in obtaining the desired microstructure or eliminating solidification defects such as porosity and segregation in cast billets. Up to now,few studies on the induced electromagnetic force （also called the Lorentz force） field in liquid metal have been reported. Compared with the magnetic field, the induced force field is the real and only direct cause for flow control. The electromagnetic force is comprised of two components. One is time-independent and the other is time- dependent. The time-dependent component varies with time in both amplitude and direction. When it reaches the extreme value,it can be one dozen times larger than the time-independent component. In this paper, a new method to quantitatively describe the induced electromagnetic force in liquid metal under a harmonic electromagnetic field,including both its time- independent and dependent components, was proposed based on the formula derivation from the data of amplitude and phase angle. Through this method ,the features of the time-dependent component were discussed, including the directions of rotation and the long axis. As a result, the force pattern was described. With two example calculations, the method was explained in detail. The results of both examples show that the force field in liquid metal can be divided into several regions with different force features. Example 1 shows the effect of coil position on the evolution of the force field pattern in liquid metal. Example 2 is a kind of stirring by the travelling magnetic field ,whose results present the sub-structures in metal and show that most of them have almost the same rotating direction.展开更多
The short-range repulsive interactions of any force field must be modified to be applicable for high energy atomic collisions because of extremely far from equilibrium state when used in molecular dynamics(MD)simulati...The short-range repulsive interactions of any force field must be modified to be applicable for high energy atomic collisions because of extremely far from equilibrium state when used in molecular dynamics(MD)simulations.In this work,the short-range repulsive interaction of a reactive force field(ReaxFF),describing Fe-Ni-Al alloy system,is well modified by adding a tabulated function form based on Ziegler-Biersack-Littmark(ZBL)potential.The modified interaction covers three ranges,including short range,smooth range,and primordial range.The short range is totally predominated by ZBL potential.The primordial range means the interactions in this range is the as-is ReaxFF with no changes.The smooth range links the short-range ZBL and primordial-range ReaxFF potentials with a taper function.Both energies and forces are guaranteed to be continuous,and qualified to the consistent requirement in LAMMPS.This modified force field is applicable for simulations of energetic particle bombardments and reproducing point defects'booming and recombination effectively.展开更多
Ab initio study of the equilibrium structure, spectroscopy constants, and anharmonic force field for several isotopomers of germanium dichloride （70GeCl2, 72GECl2, and 76GeCl2） have been carried out at the MP2 and C...Ab initio study of the equilibrium structure, spectroscopy constants, and anharmonic force field for several isotopomers of germanium dichloride （70GeCl2, 72GECl2, and 76GeCl2） have been carried out at the MP2 and CCSD（T） levels of theory using cc-pVTZ basis set. The cal- culated geometries, rotational constants, vibration-rotation interaction constants, harmonic frequencies, anharmonic constants, quartic and sextic centrifugal distortion constants, cubic and quartic force constants are compared with experimental data. For small mass differences of the Ge isotopes, the isotopic effects for germanium dichloride are much weaker. The agreements are satisfactory for these two methods, but the deviations of CCSD（T） results are slightly larger than that of MP2, because of CCSD（T）＇s inadequate treatment of electron correlation in hypervalent Cl atom.展开更多
A method was developed to quantitatively describe the time-varying Lorentz force field induced in billet under harmonic magnetic field.Based on the numerical analysis of the Lorentz force,the numeral features were con...A method was developed to quantitatively describe the time-varying Lorentz force field induced in billet under harmonic magnetic field.Based on the numerical analysis of the Lorentz force,the numeral features were concluded, which comprised of the mean force,the maximum force,the long axis,short axis and rotation direction of ellipse,the phase difference index,and so on.Using this method,the Lorentz force field in φ160 billet under 3 Hz harmonic magnetic field were analyzed.展开更多
We investigate the Hugoniot curve, shock-particle velocity relations, and Chapman-Jouguet conditions of the hot dense system through molecular dynamics （MD） simulations. The detailed pathways from crystal nitrometha...We investigate the Hugoniot curve, shock-particle velocity relations, and Chapman-Jouguet conditions of the hot dense system through molecular dynamics （MD） simulations. The detailed pathways from crystal nitromethane to reacted state by shock compression are simulated. The phase transition of N2 and CO mixture is found at about 10 GPa, and the main reason is that the dissociation of the C-O bond and the formation of C-C bond start at 10.0-11.0 GPa. The unreacted state simulations of nitromethane are consistent with shock Hugoniot data. The complete pathway from unreacted to reacted state is discussed. Through chemical species analysis, we find that the C-N bond breaking is the main event of the shock-induced nitromethane decomposition.展开更多
Developing a widely-used reactive force field is meaningful to explore the fundamental reaction mechanism on gas-surface chemical reaction dynamics due to its very high computational efficiency. We here present a stud...Developing a widely-used reactive force field is meaningful to explore the fundamental reaction mechanism on gas-surface chemical reaction dynamics due to its very high computational efficiency. We here present a study of hydrogen and its deuterated molecules dissociation on Pd surfaces based on a full-dimensional potential energy surface （PES） constructed by using a simple second moment approximation reactive force field （SMA RFF）. Although the descriptions of the adsorbate-substrate interaction contain only the dissociation reaction of H2/Pd（111） system, a good transferability of SMA potential energy surface （PES） is shown to investigate the hydrogen dissociation on Pd（100）. Our simulation results show that, the dissociation probabilities of H2 and its deuterated molecules on Pd（111） and Pd（100） surfaces keep non-monotonous variations with respect to the incident energy Ei, which is in good agreement with the previous ab initio molecular dynamics. Furthermore, for the oriented molecules, the dissociation probabilities of the oriented H2 （D2 and T2） molecule have the same orientation dependence behavior as those oriented HD （HT and DT） molecules.展开更多
Carbon nanotubes （CNTs） have long been expected to be excellent nanochannels for use in desalination membranes and other bio-inspired human-made channels owing to their experimentally confirmed ultrafast water flow ...Carbon nanotubes （CNTs） have long been expected to be excellent nanochannels for use in desalination membranes and other bio-inspired human-made channels owing to their experimentally confirmed ultrafast water flow and theoretically predicted ion rejection. The correct classical force field potential for the interactions between cations and CNTs plays a cru- cial role in understanding the transport behaviors of ions near and inside the CNT, which is key to these expectations. Here, using density functional theory calculations, we provide classical force field potentials for the interactions of Na＋/hydrated Na＋ with （7,7）, （8,8）, （9,9）, and （10,10）-type CNTs. These potentials can be directly used in current popular classical soft- ware such as nanoscale molecular dynamics （NAMD） by employing the tclBC interface. By incorporating the potential of hydrated cation-g interactions to classical all-atom force fields, we show that the ions will move inside the CNT and accu- mulate, which will block the water flow in wide CNTs. This blockage of water flow in wide CNTs is consistent with recent experimental observations. These results will be helpful for the understanding and design of desalination membranes, new types of nanofluidic channels, nanosensors, and nanoreactors based on CNT platforms.展开更多
A new approach to detecting ocean eddies automatically from remote sensing imageries based on the ocean eddy＇s eigen-pattern in remote sensing imagery and ＂force field-based shape extracting method＂ is proposed. Fi...A new approach to detecting ocean eddies automatically from remote sensing imageries based on the ocean eddy＇s eigen-pattern in remote sensing imagery and ＂force field-based shape extracting method＂ is proposed. First, the analysis on extracting eddies＇ edges from remote sensing imagery using conventional edge detection arithmetic operators is performed and returns digitized vector edge data as a result. Second, attraction forces and fusion forces between edge curves were analyzed and calculated based on the vector eddy edges. Thirdly, the virtual significant spatial patterns of eddy were detected automatically using iterative repetition followed by optimized rule. Finally, the spatial form auto-detection of different types of ocean eddies was done using satellite images. The study verified that this is an effective way to identify and detect the ocean eddy with a complex form.展开更多
The relationship between the partition ratio at a solid-liquid interface and the temperature gradient or the external force field has been theoretically analysed.It is shown that under the influence of a temperature g...The relationship between the partition ratio at a solid-liquid interface and the temperature gradient or the external force field has been theoretically analysed.It is shown that under the influence of a temperature gradient or an external force field,the partition ratio at a solid-liquid interface will deviate from the equilibrium value.展开更多
The harmonic force field and the vibrational spectrum of nitramide were calculated by using the ab initio gradient program TEXAS at the Hartree-Fock level with a 4-21G basis set. The directly computed theoretical harm...The harmonic force field and the vibrational spectrum of nitramide were calculated by using the ab initio gradient program TEXAS at the Hartree-Fock level with a 4-21G basis set. The directly computed theoretical harmonic force field was scaled by using empirical scale factors which are transferred from other molecules and provided an a priori prediction of fundamental frequencies and intensities. The average deviations between predicted vibrational frequencies of nitramide and experimental IR spectrum in an argon matrix are 63 cm-1 for symmetric vibrations and 41 cm-1 for antisymmetric modes. A new set of scale factors was optimized in this paper. These scale factors reduced the average deviations to 2. 3 cm-1 for symmetric modes and 0. 8 cm-1 for antisymmetric ones. The vibrational spectra of three isotopic derivatives of nitramide were predicted by using the force field resulted from the optimized set of scale factors, which are in good agreement with their experimental data in an argon matrix.展开更多
Cobalt-protein complexes play an important role in biochemical processes.The structure of the model molecule,Co(H_2O)_3SO_4(phen) has been studied by molecular mechanics.The molecular force field (MM2) parameters have...Cobalt-protein complexes play an important role in biochemical processes.The structure of the model molecule,Co(H_2O)_3SO_4(phen) has been studied by molecular mechanics.The molecular force field (MM2) parameters have been developed for the particular class of the complexes.展开更多
It is shown that the introduction of thermal effect, zero-point vibration, and phonon anharmonicity to a high quality and first-principle-Sased force field （atomic potential） results in a significant improvement in ...It is shown that the introduction of thermal effect, zero-point vibration, and phonon anharmonicity to a high quality and first-principle-Sased force field （atomic potential） results in a significant improvement in predict- ing the densities for the α phase crystalline hexahydro-1,3,5-trinitro-l,3,5-triazine （RDX）, and derivation of its high-fidelity Hugoniot locus and Mie-Grfineisen equation of state covering a very wide range of pressures and temperatures. This work can be used to efficiently and accurately predict the thermophysical properties of solid explosives over the pressures and temperatures to which they are subjected, which is a long-standing issue in the field of energetic materials.展开更多
The particle migrating behavior at solidifying front is discussed in theory with the application of electromagnetic force field(EMFF), on the basis of foregone analysis of force upon particle ahead of solidifying fron...The particle migrating behavior at solidifying front is discussed in theory with the application of electromagnetic force field(EMFF), on the basis of foregone analysis of force upon particle ahead of solidifying front without electromagnetic force field. The critical solidification velocities of particle pushing/engulfment transition ahead of horizontal and vertical interface are derived respectively when a certain EMFF is applied. And the critical electromagnetic forces of particle pushing/engulfment transition ahead of horizontal and vertical interface are also derived separately when a certain solidifying velocity is given.展开更多
The reactive force field was used to study the molecular dynamics of cross-linked EPON 862 （diglycidyl ether of bisphenol-F） and DETDA （diethylene toluene diamine） system in order to predict its thermo-mechanical ...The reactive force field was used to study the molecular dynamics of cross-linked EPON 862 （diglycidyl ether of bisphenol-F） and DETDA （diethylene toluene diamine） system in order to predict its thermo-mechanical behavior under different loading conditions. The approach for building the EPON 862/DETDA structures, cross-linking, and equilibration of the systems, and the evaluation of the models are presented. The mechanical properties such as Young＇s and shear moduli, Poisson ratio, and yields strength as well as thermal properties such as glass transition temperature and coefficient of thermal expansion are predicted. The results are in close agreement with both experimental data and simulated results in literature.展开更多
We present a new method for image deformation. The warping technique provides smooth distortion with intuitive and easy manipulation. Driven by a restrained force field, the input image is deformed gradually and conti...We present a new method for image deformation. The warping technique provides smooth distortion with intuitive and easy manipulation. Driven by a restrained force field, the input image is deformed gradually and continuously. The method allows us to customize the force fields and the region of interest manually through some simple steps. Experimental results demonstrate the effectiveness and convenience of the approach.展开更多
基金funding support from the National Natural Science Foundation of China(92472109,T2325012)the Program for HUST Academic Frontier Youth Team+1 种基金support from the Fundamental Research Funds for the Central Universities(HUST,5003120083)supported by the Postdoctoral Fellowship Program of CPSF(GZC20240532)。
文摘Batteries play a critical role in electric vehicles and distributed energy generation.With the growing demand for energy storage solutions,new battery materials and systems are continually being developed.In this process,molecular dynamics(MD)simulations can reveal the microscopic mechanisms of battery processes,thereby boosting the design of batteries.Compared to other MD simulation techniques,the machine learning force field(MLFF)holds the advantages of first-principles accuracy along with large spatial and temporal scale,offering opportunities to uncover new mechanisms in battery systems.This review presents a detailed overview of the fundamental principles and model types of MLFFs,as well as their applications in simulating the structure,transport properties,and chemical reaction properties of bulk battery materials and interfaces.Notably,we emphasize the long-range interaction corrections and constant-potential methods in the model design of MLFFs.Finally,we discuss the challenges and prospects of applying MLFF models in the research of batteries.
基金supported by the Natural Science Foundation of Inner Mongolia(No.2020MS01023).
文摘The interstellar medium molecule thiocarbonyl thioketen,H_(2)CCS,has several stable isomers and has received considerable attention of as-tronomical observation in recent years.The positions of H,C,and S atoms of three isomers lead to di-verse dipole moments and spectro-scopic constants.The anharmonic force field and spectroscopic con-stants of thiocarbonyl thioketen and its isomers are calculated using MP2,B3LYP,and CCSD(T)methods employing correlation consistent basis sets.Molecule structures,rotational spectroscopic constants,and fundamental frequencies are compared with the available experimental data for thiocarbonyl thioketen.Ro-vibrational interaction constants,anharmonic constants,cubic and quartic force constants are predicted for thiocarbonyl thioketen.In addition,some rotational and vibrational spectroscopic parameters are predict-ed with the same level of theory for thioacetylene,HCCSH,and thiirene,(CH)_(2)S.The predic-tions of these spectroscopic constants are expected to guide the future astronomical observa-tion and high resolution experimental work for C_(2)H_(2)S isomers.
基金supported by the National Natural Science Foundation of China(No.22273002)the National Key Research and Development Program of China(No.2022YFB4101401).We acknowledge the High-performance Computing Platform of Peking University for providing the computational facility.
文摘Bimetallic surfaces play a pivotal role in heterogeneous catalysis,yet their theoretical modeling has long been hindered by the computational chal-lenges of capturing configurational disorder,a critical feature governing their catalytic properties.Tradition-al approaches rely on oversimplified ordered surface models or restrict dis-order to a few atomic layers,limiting their predictive power.Here,we Cu_(1-x)Zn_(x)Cu_(1-x)Zn_(x)present an accurate and efficient computational framework that integrates machine learning force fields(MLFFs)with the cluster expansion(CE)method to study configurationally dis-ordered bimetallic surfaces at finite temperatures.We have developed an efficient workflow in which the MLFF is first trained iteratively via an active learning protocol,and then used to generate accurate energetic data for thousands of configurations that enable robust CE model construction.By treating bulk and surface clusters separately,we can build CE models for surface slabs with an arbitrary number of layers.Using as a case study,our CE-based Monte Carlo simulations reveal key structural insights that are relevant to the under-standing of catalytic properties of surfaces.This work demonstrates how MLFF-aided CE can overcome traditional limitations in theoretical modeling of bimetallic surfaces and highlights pathways toward more realistic modeling of heterogeneous catalysts.
基金supported by the National Natural Science Foundation of China(Nos.52303116,52403125)the Natural Science Foundation of Hunan Province(No.2024JJ6461)+2 种基金the Science and Technology Innovation Program of Hunan Province(Nos.2022RC1080,2023RC3006)the Innovation Research Foundation of NUDT(Nos.22-ZZCX-076 and 23-ZZCX-ZZGC-01-10)the Key Research and Development Program of Hunan Province of China(No.2023ZJ1040).
文摘Large-scale molecular dynamics(MD) simulations of crosslinked epoxy with quantum-level accuracy while capturing complex reactivity is a compelling yet unrealized challenge. In this work, through the construction of a chemical-environment-directing dataset, a reactive machine learning force field that accurately captures both reactive events and thermos-mechanical properties is developed. The force field achieves energy and force root-mean-square errors of 1.3 meV/atom and 159 meV/A, respectively, and operates approximately 1200 times faster than ab initio molecular dynamics. MD simulations demonstrate excellent predictive capabilities across multiple critical thermos-mechanical properties(radial distribution function, density, and elastic modulus), with results being well consistent with experimental values. In particular, the force field can provide accurate prediction of the bond dissociation energies for typical bonds with a mean absolute error of 7.8 kcal/mol(<8%), which enables the simulation of tensile-induced failure caused by chemical bond breaking. Our work demonstrates the capability of the machine learning force field to handle the extraordinary complexity of crosslinked epoxy systems, providing a valuable blueprint for future development of more generalized reactive force fields applicable to most polymers.
基金the useful discussion.This work is supported by the Natural Science Foundation of Zhe-jiang Province(Grant No.LQ22A040010)the National Natural Science Foundation of China(Grant Nos.12304545 and 12204434).
文摘Levitated optomechanical systems represent an excellent candidate platform for force and acceleration sensing.We propose a force-sensing protocol utilizing an optically levitated nanoparticle array.In our scheme,N nanoparticles are trapped in an optical cavity using holographic optical tweezers.An external laser drives the cavity,exciting N cavity modes interacting simultaneously with the N nanoparticles.The optomechanical interaction encodes the information of the force acting on each nanoparticle onto the intracavity photons,which can be detected directly at the output ports of the cavity.Consequently,our protocol enables real-time imaging of a force field.
文摘In modern processing of conducting materials, such as steel,the time-varying electromagnetic field plays a key role in obtaining the desired microstructure or eliminating solidification defects such as porosity and segregation in cast billets. Up to now,few studies on the induced electromagnetic force （also called the Lorentz force） field in liquid metal have been reported. Compared with the magnetic field, the induced force field is the real and only direct cause for flow control. The electromagnetic force is comprised of two components. One is time-independent and the other is time- dependent. The time-dependent component varies with time in both amplitude and direction. When it reaches the extreme value,it can be one dozen times larger than the time-independent component. In this paper, a new method to quantitatively describe the induced electromagnetic force in liquid metal under a harmonic electromagnetic field,including both its time- independent and dependent components, was proposed based on the formula derivation from the data of amplitude and phase angle. Through this method ,the features of the time-dependent component were discussed, including the directions of rotation and the long axis. As a result, the force pattern was described. With two example calculations, the method was explained in detail. The results of both examples show that the force field in liquid metal can be divided into several regions with different force features. Example 1 shows the effect of coil position on the evolution of the force field pattern in liquid metal. Example 2 is a kind of stirring by the travelling magnetic field ,whose results present the sub-structures in metal and show that most of them have almost the same rotating direction.
基金Project supported by the National Magnetic Confinement Fusion Energy Research Project(Grant Nos.2019YFE03120003,2018YFE0307100,and 2017YFE0302500)the National Natural Science Foundation of China(Grant Nos.11975034,11921006,12004010,and U20B2025).
文摘The short-range repulsive interactions of any force field must be modified to be applicable for high energy atomic collisions because of extremely far from equilibrium state when used in molecular dynamics(MD)simulations.In this work,the short-range repulsive interaction of a reactive force field(ReaxFF),describing Fe-Ni-Al alloy system,is well modified by adding a tabulated function form based on Ziegler-Biersack-Littmark(ZBL)potential.The modified interaction covers three ranges,including short range,smooth range,and primordial range.The short range is totally predominated by ZBL potential.The primordial range means the interactions in this range is the as-is ReaxFF with no changes.The smooth range links the short-range ZBL and primordial-range ReaxFF potentials with a taper function.Both energies and forces are guaranteed to be continuous,and qualified to the consistent requirement in LAMMPS.This modified force field is applicable for simulations of energetic particle bombardments and reproducing point defects'booming and recombination effectively.
文摘Ab initio study of the equilibrium structure, spectroscopy constants, and anharmonic force field for several isotopomers of germanium dichloride （70GeCl2, 72GECl2, and 76GeCl2） have been carried out at the MP2 and CCSD（T） levels of theory using cc-pVTZ basis set. The cal- culated geometries, rotational constants, vibration-rotation interaction constants, harmonic frequencies, anharmonic constants, quartic and sextic centrifugal distortion constants, cubic and quartic force constants are compared with experimental data. For small mass differences of the Ge isotopes, the isotopic effects for germanium dichloride are much weaker. The agreements are satisfactory for these two methods, but the deviations of CCSD（T） results are slightly larger than that of MP2, because of CCSD（T）＇s inadequate treatment of electron correlation in hypervalent Cl atom.
文摘A method was developed to quantitatively describe the time-varying Lorentz force field induced in billet under harmonic magnetic field.Based on the numerical analysis of the Lorentz force,the numeral features were concluded, which comprised of the mean force,the maximum force,the long axis,short axis and rotation direction of ellipse,the phase difference index,and so on.Using this method,the Lorentz force field in φ160 billet under 3 Hz harmonic magnetic field were analyzed.
基金supported by the National Natural Science Foundation of China(Grant No.11374217)the Shandong Provincial Natural Science Foundation,China(Grant No.ZR2014BQ008)
文摘We investigate the Hugoniot curve, shock-particle velocity relations, and Chapman-Jouguet conditions of the hot dense system through molecular dynamics （MD） simulations. The detailed pathways from crystal nitromethane to reacted state by shock compression are simulated. The phase transition of N2 and CO mixture is found at about 10 GPa, and the main reason is that the dissociation of the C-O bond and the formation of C-C bond start at 10.0-11.0 GPa. The unreacted state simulations of nitromethane are consistent with shock Hugoniot data. The complete pathway from unreacted to reacted state is discussed. Through chemical species analysis, we find that the C-N bond breaking is the main event of the shock-induced nitromethane decomposition.
基金This work was supported by the National Natural Science Foundation of China （No.21506053） and Doctoral Scientific Research Foundation Project （KYY15023）.
文摘Developing a widely-used reactive force field is meaningful to explore the fundamental reaction mechanism on gas-surface chemical reaction dynamics due to its very high computational efficiency. We here present a study of hydrogen and its deuterated molecules dissociation on Pd surfaces based on a full-dimensional potential energy surface （PES） constructed by using a simple second moment approximation reactive force field （SMA RFF）. Although the descriptions of the adsorbate-substrate interaction contain only the dissociation reaction of H2/Pd（111） system, a good transferability of SMA potential energy surface （PES） is shown to investigate the hydrogen dissociation on Pd（100）. Our simulation results show that, the dissociation probabilities of H2 and its deuterated molecules on Pd（111） and Pd（100） surfaces keep non-monotonous variations with respect to the incident energy Ei, which is in good agreement with the previous ab initio molecular dynamics. Furthermore, for the oriented molecules, the dissociation probabilities of the oriented H2 （D2 and T2） molecule have the same orientation dependence behavior as those oriented HD （HT and DT） molecules.
基金Project supported by the National Science Fund for Outstanding Young Scholars of China(Grant No.11722548)the National Natural Science Foundation of China(Grant Nos.11574339 and 11404361)
文摘Carbon nanotubes （CNTs） have long been expected to be excellent nanochannels for use in desalination membranes and other bio-inspired human-made channels owing to their experimentally confirmed ultrafast water flow and theoretically predicted ion rejection. The correct classical force field potential for the interactions between cations and CNTs plays a cru- cial role in understanding the transport behaviors of ions near and inside the CNT, which is key to these expectations. Here, using density functional theory calculations, we provide classical force field potentials for the interactions of Na＋/hydrated Na＋ with （7,7）, （8,8）, （9,9）, and （10,10）-type CNTs. These potentials can be directly used in current popular classical soft- ware such as nanoscale molecular dynamics （NAMD） by employing the tclBC interface. By incorporating the potential of hydrated cation-g interactions to classical all-atom force fields, we show that the ions will move inside the CNT and accu- mulate, which will block the water flow in wide CNTs. This blockage of water flow in wide CNTs is consistent with recent experimental observations. These results will be helpful for the understanding and design of desalination membranes, new types of nanofluidic channels, nanosensors, and nanoreactors based on CNT platforms.
文摘A new approach to detecting ocean eddies automatically from remote sensing imageries based on the ocean eddy＇s eigen-pattern in remote sensing imagery and ＂force field-based shape extracting method＂ is proposed. First, the analysis on extracting eddies＇ edges from remote sensing imagery using conventional edge detection arithmetic operators is performed and returns digitized vector edge data as a result. Second, attraction forces and fusion forces between edge curves were analyzed and calculated based on the vector eddy edges. Thirdly, the virtual significant spatial patterns of eddy were detected automatically using iterative repetition followed by optimized rule. Finally, the spatial form auto-detection of different types of ocean eddies was done using satellite images. The study verified that this is an effective way to identify and detect the ocean eddy with a complex form.
文摘The relationship between the partition ratio at a solid-liquid interface and the temperature gradient or the external force field has been theoretically analysed.It is shown that under the influence of a temperature gradient or an external force field,the partition ratio at a solid-liquid interface will deviate from the equilibrium value.
基金Supported by the National Natural Science Foundation of China
文摘The harmonic force field and the vibrational spectrum of nitramide were calculated by using the ab initio gradient program TEXAS at the Hartree-Fock level with a 4-21G basis set. The directly computed theoretical harmonic force field was scaled by using empirical scale factors which are transferred from other molecules and provided an a priori prediction of fundamental frequencies and intensities. The average deviations between predicted vibrational frequencies of nitramide and experimental IR spectrum in an argon matrix are 63 cm-1 for symmetric vibrations and 41 cm-1 for antisymmetric modes. A new set of scale factors was optimized in this paper. These scale factors reduced the average deviations to 2. 3 cm-1 for symmetric modes and 0. 8 cm-1 for antisymmetric ones. The vibrational spectra of three isotopic derivatives of nitramide were predicted by using the force field resulted from the optimized set of scale factors, which are in good agreement with their experimental data in an argon matrix.
基金Project supported by the National Natural Science Foundation of China.
文摘Cobalt-protein complexes play an important role in biochemical processes.The structure of the model molecule,Co(H_2O)_3SO_4(phen) has been studied by molecular mechanics.The molecular force field (MM2) parameters have been developed for the particular class of the complexes.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11372053,11402031,11221202 and 11172044the Opening Project of the State Key Laboratory of Explosion Science and Technology under Grant No KFJJ14-06M
文摘It is shown that the introduction of thermal effect, zero-point vibration, and phonon anharmonicity to a high quality and first-principle-Sased force field （atomic potential） results in a significant improvement in predict- ing the densities for the α phase crystalline hexahydro-1,3,5-trinitro-l,3,5-triazine （RDX）, and derivation of its high-fidelity Hugoniot locus and Mie-Grfineisen equation of state covering a very wide range of pressures and temperatures. This work can be used to efficiently and accurately predict the thermophysical properties of solid explosives over the pressures and temperatures to which they are subjected, which is a long-standing issue in the field of energetic materials.
基金Supported by the Science Foundation of Shanghai Municipal Commission of Scienceand Technology!( 97JC1 41 0 7)
文摘The particle migrating behavior at solidifying front is discussed in theory with the application of electromagnetic force field(EMFF), on the basis of foregone analysis of force upon particle ahead of solidifying front without electromagnetic force field. The critical solidification velocities of particle pushing/engulfment transition ahead of horizontal and vertical interface are derived respectively when a certain EMFF is applied. And the critical electromagnetic forces of particle pushing/engulfment transition ahead of horizontal and vertical interface are also derived separately when a certain solidifying velocity is given.
文摘The reactive force field was used to study the molecular dynamics of cross-linked EPON 862 （diglycidyl ether of bisphenol-F） and DETDA （diethylene toluene diamine） system in order to predict its thermo-mechanical behavior under different loading conditions. The approach for building the EPON 862/DETDA structures, cross-linking, and equilibration of the systems, and the evaluation of the models are presented. The mechanical properties such as Young＇s and shear moduli, Poisson ratio, and yields strength as well as thermal properties such as glass transition temperature and coefficient of thermal expansion are predicted. The results are in close agreement with both experimental data and simulated results in literature.
文摘We present a new method for image deformation. The warping technique provides smooth distortion with intuitive and easy manipulation. Driven by a restrained force field, the input image is deformed gradually and continuously. The method allows us to customize the force fields and the region of interest manually through some simple steps. Experimental results demonstrate the effectiveness and convenience of the approach.
