Effect of translational and angular momentum conservation on energy equipartition in microcanonical equilibrium in small clusters
Effect of translational and angular momentum conservation on energy equipartition in microcanonical equilibrium in small clusters
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DOI：
10.1103/physreve.79.051101
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发表时间：
2009-05-01
影响因子：
2.4
通讯作者：
Ikeda, Kensuke S.
中科院分区：
文献类型：
--
作者：
Niiyama, Tomoaki;Shimizu, Yasushi;Ikeda, Kensuke S.
我们用数值和分析的方法研究了总平动动量和角动量守恒对具有少量自由度的微正则粒子系统（特别是微团簇）中粒子间动能分布的影响。利用Lennard-Jones、Morse和Coulomb + born - mayer型势对总能量和动量恒定的微团簇进行分子动力学模拟，结果表明，即使在热平衡状态下，粒子间的动能分布也可能是不均匀的，并且取决于粒子的质量和位置。考虑到额外的守恒量，使用微正则测度的统计分析给出了动能作为粒子质量和位置的函数的理论表达式，与麦克斯韦-玻尔兹曼分布的偏差只有0 （1/N-2）。这些表达式与数值结果吻合较好。最后，我们对动能分布的不均匀性提出了一个直观的解释。
We investigate numerically and analytically the effects of conservation of total translational and angular momentum on the distribution of kinetic energy among particles in microcanonical particle systems with small number of degrees of freedom, specifically microclusters. Molecular dynamics simulations of microclusters with constant total energy and momenta, using Lennard-Jones, Morse, and Coulomb plus Born-Mayer-type potentials, show that the distribution of kinetic energy among particles can be inhomogeneous and depend on particle mass and position even in thermal equilibrium. Statistical analysis using a microcanonical measure taking into account of the additional conserved quantities gives theoretical expressions for kinetic energy as a function of the mass and position of a particle with only O(1/N-2) deviation from the Maxwell-Boltzmann distribution. These expressions fit numerical results well. Finally, we propose an intuitive interpretation for the inhomogeneity of the kinetic energy distributions.