Three coalescence processes of Cu57-Cu57, Cu57-Cu58, and Cu5s Cu58 clusters at 300 K are investigated by employing molecular dynamics simulations. According to the evolutions of mean square displacement and local atom...Three coalescence processes of Cu57-Cu57, Cu57-Cu58, and Cu5s Cu58 clusters at 300 K are investigated by employing molecular dynamics simulations. According to the evolutions of mean square displacement and local atom packing, the coalescence process can be separated into three stages including an approaching stage, a coalescing stage, and a coalesced stage. The simulations show that the coalescence processes and the formed products are sensitive to the respective initial structures of, and the relative configuration between, the two coalescing icosahedron-based clusters.展开更多
The surface melting process of structure sI methane hydrate is simulated at T = 240, 260, 280, and 300 K using NVT molecular dynamics method. The simulation results show that a quasi-liquid layer will be formed during...The surface melting process of structure sI methane hydrate is simulated at T = 240, 260, 280, and 300 K using NVT molecular dynamics method. The simulation results show that a quasi-liquid layer will be formed during the melting process. The density distribution, translation, orientation, and dynamic properties of water molecules in the quasi-liquid layer are calculated as a function of the distance normal to the interface, which indicates the performance of quasi-liquid layer exhibits a continuous change from crystal-like to liquid-like. The quasi-liquid layer plays as a resistance of mass transfer restraining the diffusion of water and methane molecules during the melting process. The resistance of quasi-liquid layer will restrain methane molecules diffuse from hydrate phase to gas phase and slow the melting process, which can be considered as a possible mechanism of self-preservation effect. The performance of quasi-liquid layer is more crystal-like when the temperature is lower than the melt- ing-point of water, which will exhibit an obvious self-preservation. The self-preservation will weaken while the temperature is higher than the melting-point of water because of the liquid-like performance of the quasi-liquid layer.展开更多
We report on molecular dynamics simulations performed using microcanonical ensemble to predict the melting of argon particles in nanometer size range 10 nm and to investigate the effect of the time step integration. W...We report on molecular dynamics simulations performed using microcanonical ensemble to predict the melting of argon particles in nanometer size range 10 nm and to investigate the effect of the time step integration. We use the Lennard- Jones potential functions to describe the interatomic interactions, and the results are evaluated by using caloric curves of the melting phenomenon. Thermodynamic properties, including the total energy, Lindemann parameter, kinetic and potential distribution’s functions, are used to characterize the melting process. The data shows bimodal behavior only in a certain interval of integration time step Δt, while the internal energy increases monotonically with the temperature. For the other time step values, the back bending disappears. We claim that negative specific heat is related to a possible decrease of entropy in an isolated system;this can be interpreted as a result of the internal interactions, especially attractive process and specific relaxation time.展开更多
The surface diffusion of Pt dimers on Wulff polyhedral clusters with 586-12934 atoms was studied by the embedded atom method. The minimum energy diffusion path and the corresponding energy barrier for dimer diffusion ...The surface diffusion of Pt dimers on Wulff polyhedral clusters with 586-12934 atoms was studied by the embedded atom method. The minimum energy diffusion path and the corresponding energy barrier for dimer diffusion on cluster surfaces were determined through a combination of the quenched Molecular Dynamics and the Nudged Elastic Band method. It was found that the diffusion of a dimer across the step-edge by dissociation and consecutive single-atom exchange with the edge atoms, rather than diffusion over the edge as a unit. Therefore, the step can enhance the dissociation of the dimer. For small Wulff polyhedral clusters containing up to 2000 atoms, the energy barrier for dimer diffusion from the {111} to the {100} facet is almost equal to that for the single adatom diffusion on the flat {111} surface. From the calculated cluster size dependence of the energy barrier, we conclude that the Wulff polyhedral cluster is stable, as the cluster has more than about 2000 atoms.展开更多
Atomic cluster-based networks represent a promising architecture for the realization of neuromorphic computing systems,which may overcome some of the limitations of the current computing paradigm.The formation and bre...Atomic cluster-based networks represent a promising architecture for the realization of neuromorphic computing systems,which may overcome some of the limitations of the current computing paradigm.The formation and breakage of links between the clusters are of utmost importance for the functioning of these computing systems.This paper reports the results of molecular dynamics simulations of synapse(bridge)formation at elevated temperature and thermal breaking processes between 2.8 nmsized Au1415 clusters deposited on a carbon substrate,a model system.Crucially,we find that the bridge formation process is driven by the diffusion of gold atoms along the substrate,no matter how small the gap between the clusters themselves.The complementary simulations of the bridge breaking process reveal the existence of a threshold bias voltage to activate bridge rupture via Joule heating.These results provide an atomistic-level understanding of the fundamental dynamical processes occurring in neuromorphic cluster arrays.展开更多
基金Supported by Special Foundation for State Major Basic Research Program of China (Grant No. G2006CB605103)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,China and the Fundamental Research Funds for the Central University (Grant No. 90405001)
文摘Three coalescence processes of Cu57-Cu57, Cu57-Cu58, and Cu5s Cu58 clusters at 300 K are investigated by employing molecular dynamics simulations. According to the evolutions of mean square displacement and local atom packing, the coalescence process can be separated into three stages including an approaching stage, a coalescing stage, and a coalesced stage. The simulations show that the coalescence processes and the formed products are sensitive to the respective initial structures of, and the relative configuration between, the two coalescing icosahedron-based clusters.
基金Supported by the National Natural Science Foundation of China (Grant No. 20221603)
文摘The surface melting process of structure sI methane hydrate is simulated at T = 240, 260, 280, and 300 K using NVT molecular dynamics method. The simulation results show that a quasi-liquid layer will be formed during the melting process. The density distribution, translation, orientation, and dynamic properties of water molecules in the quasi-liquid layer are calculated as a function of the distance normal to the interface, which indicates the performance of quasi-liquid layer exhibits a continuous change from crystal-like to liquid-like. The quasi-liquid layer plays as a resistance of mass transfer restraining the diffusion of water and methane molecules during the melting process. The resistance of quasi-liquid layer will restrain methane molecules diffuse from hydrate phase to gas phase and slow the melting process, which can be considered as a possible mechanism of self-preservation effect. The performance of quasi-liquid layer is more crystal-like when the temperature is lower than the melt- ing-point of water, which will exhibit an obvious self-preservation. The self-preservation will weaken while the temperature is higher than the melting-point of water because of the liquid-like performance of the quasi-liquid layer.
文摘We report on molecular dynamics simulations performed using microcanonical ensemble to predict the melting of argon particles in nanometer size range 10 nm and to investigate the effect of the time step integration. We use the Lennard- Jones potential functions to describe the interatomic interactions, and the results are evaluated by using caloric curves of the melting phenomenon. Thermodynamic properties, including the total energy, Lindemann parameter, kinetic and potential distribution’s functions, are used to characterize the melting process. The data shows bimodal behavior only in a certain interval of integration time step Δt, while the internal energy increases monotonically with the temperature. For the other time step values, the back bending disappears. We claim that negative specific heat is related to a possible decrease of entropy in an isolated system;this can be interpreted as a result of the internal interactions, especially attractive process and specific relaxation time.
基金Project supported by the National Natural Science Foundation of China （Grant No 50572013） and the National Basic Research Program of China （Grant No 2006CB605103）. Corresponding author.
基金supported by the National Natural Science Foundation of China (Grant No. 50971058)the Hunan Provincial Natural Science Foundation of China (Grant No. 10JJ3050)
文摘The surface diffusion of Pt dimers on Wulff polyhedral clusters with 586-12934 atoms was studied by the embedded atom method. The minimum energy diffusion path and the corresponding energy barrier for dimer diffusion on cluster surfaces were determined through a combination of the quenched Molecular Dynamics and the Nudged Elastic Band method. It was found that the diffusion of a dimer across the step-edge by dissociation and consecutive single-atom exchange with the edge atoms, rather than diffusion over the edge as a unit. Therefore, the step can enhance the dissociation of the dimer. For small Wulff polyhedral clusters containing up to 2000 atoms, the energy barrier for dimer diffusion from the {111} to the {100} facet is almost equal to that for the single adatom diffusion on the flat {111} surface. From the calculated cluster size dependence of the energy barrier, we conclude that the Wulff polyhedral cluster is stable, as the cluster has more than about 2000 atoms.
基金The authors are grateful for partial financial support by the European Commission through the RADON project(GA 872494)within the H2020-MSCA-RISE-2019 callThis article is also based upon work from the COST Action CA20129 MultIChem,supported by COST(European Cooperation in Science and Technology)+1 种基金TP acknowledges Swansea University support via project 74143 of the Research Committee of Aristotle University of ThessalonikiThis work was also supported in part by Deutsche Forschungsgemeinschaft(Project no.415716638).The authors acknowledge the computational support by the Goethe-HLR cluster of the Frankfurt Center for Scientific Computing and by the Supercomputing Wales project,which is part-funded by the European Regional Development Fund(ERDF)via the Welsh Government.
文摘Atomic cluster-based networks represent a promising architecture for the realization of neuromorphic computing systems,which may overcome some of the limitations of the current computing paradigm.The formation and breakage of links between the clusters are of utmost importance for the functioning of these computing systems.This paper reports the results of molecular dynamics simulations of synapse(bridge)formation at elevated temperature and thermal breaking processes between 2.8 nmsized Au1415 clusters deposited on a carbon substrate,a model system.Crucially,we find that the bridge formation process is driven by the diffusion of gold atoms along the substrate,no matter how small the gap between the clusters themselves.The complementary simulations of the bridge breaking process reveal the existence of a threshold bias voltage to activate bridge rupture via Joule heating.These results provide an atomistic-level understanding of the fundamental dynamical processes occurring in neuromorphic cluster arrays.
