Mechanical Simulation of the Pressure and the Relaxation to Thermal Equilibrium of a Hot and Dense Rare Gas Cluster

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• 作者：A. Gross ; R. D. Levine
• 刊名：Journal of Physical Chemistry B
• 出版年：2006
• 出版时间：November 30, 2006
• 年：2006
• 卷：110
• 期：47
• 页码：24070 - 24076
• 全文大小：90K
• 年卷期：v.110,no.47(November 30, 2006)
• ISSN：1520-5207

文摘

A cold atomic cluster can be very rapidly heated and compressed by a hypersonic impact at a hard surface.The impact can be simulated by computing a classical trajectory for the motion of the atoms. By suddenlyconfining the hot and dense cluster within a rigid container, it is possible to monitor the time evolution of theforce acting on the faces of the container. It is found that the pressure computed this way very rapidly decaysto a time-independent value. After a somewhat longer time, this value reproduces the value for the pressurecomputed as the sum of the kinetic and internal pressures. This agreement is expected for a system inequilibrium. These observations support the conclusion that there is a fast relaxation to thermal equilibriumin these essentially hard-sphere systems. The deviation from equilibrium is primarily due to the propagationof shock waves within the cluster. The equilibrium pressure can reach up to the megabar range.