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
Molecular dynamics simulations adopting the Born-Mayer-Huggins potential function are performed on (KBr)108, (KBr)256, (KBr)500 and (KBr)864 clusters to analyze structural, energetic, and kinetic aspects of phase chan...Molecular dynamics simulations adopting the Born-Mayer-Huggins potential function are performed on (KBr)108, (KBr)256, (KBr)500 and (KBr)864 clusters to analyze structural, energetic, and kinetic aspects of phase changes. Melting and freezing are reproducible when clusters are heated and cooled. Various diagnostic methods, including the total energy curves, the Lindemann indices, and pair-correlation functions, are used to characterize phase changes during heating and cooling stages. Results demonstrate that the melted clusters are not spherical in shape. On the other hand, the melting temperatures and heats of fusion decrease approximately linearly with the reciprocals of cluster radii. The melting point and heat of fusion for bulk KBr obtained by extrapolation are close to the experimental values.展开更多
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.
文摘Molecular dynamics simulations adopting the Born-Mayer-Huggins potential function are performed on (KBr)108, (KBr)256, (KBr)500 and (KBr)864 clusters to analyze structural, energetic, and kinetic aspects of phase changes. Melting and freezing are reproducible when clusters are heated and cooled. Various diagnostic methods, including the total energy curves, the Lindemann indices, and pair-correlation functions, are used to characterize phase changes during heating and cooling stages. Results demonstrate that the melted clusters are not spherical in shape. On the other hand, the melting temperatures and heats of fusion decrease approximately linearly with the reciprocals of cluster radii. The melting point and heat of fusion for bulk KBr obtained by extrapolation are close to the experimental values.
基金Projects(51661005,U1612442)supported by the National Natural Science Foundation of ChinaProject(QKHJC[2017]1025)supported by the Natural Science Foundation of Guizhou Province,ChinaProject(2018JJ3560)supported by the Natural Science Foundation of Hunan Province,China。
