Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan.
J Chem Phys. 2013 Aug 14;139(6):064103. doi: 10.1063/1.4817194.
Decomposition-order dependence of time development integrator on ensemble averages for the Nosé-Hoover dynamics is discussed. Six integrators were employed for comparison, which were extensions of the velocity-Verlet or position-Verlet algorithm. Molecular dynamics simulations by these integrators were performed for liquid-argon systems with several different time steps and system sizes. The obtained ensemble averages of temperature and potential energy were shifted from correct values depending on the integrators. These shifts increased in proportion to the square of the time step. Furthermore, the shifts could not be removed by increasing the number of argon atoms. We show the origin of these ensemble-average shifts analytically. Our discussion can be applied not only to the liquid-argon system but also to all MD simulations with the Nosé-Hoover thermostat. Our recommended integrators among the six integrators are presented to obtain correct ensemble averages.
讨论了 Nosé-Hoover 动力学中，对系综平均的时间发展积分器的分解阶数的依赖性。比较了六种积分器，它们都是速度-Verlet 或位置-Verlet 算法的扩展。通过这些积分器对具有不同时间步长和系统大小的液体氩系统进行分子动力学模拟。根据积分器的不同，得到的温度和势能的系综平均值从正确值发生了偏移。这些偏移与时间步长的平方成正比增加。此外，通过增加氩原子的数量并不能消除这些偏移。我们从分析上展示了这些系综平均值偏移的来源。我们的讨论不仅可以应用于液体氩系统，还可以应用于所有带有 Nosé-Hoover 热库的 MD 模拟。我们为获得正确的系综平均值，推荐了这六种积分器中的两种。
