Oberhofer Harald, Dellago Christoph, Geissler Phillip L
Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria.
J Phys Chem B. 2005 Apr 14;109(14):6902-15. doi: 10.1021/jp044556a.
We have investigated the maximum computational efficiency of reversible work calculations that change control parameters in a finite amount of time. Because relevant nonequilibrium averages are slow to converge, a bias on the sampling of trajectories can be beneficial. Such a bias, however, can also be employed in conventional methods for computing reversible work, such as thermodynamic integration or umbrella sampling. We present numerical results for a simple one-dimensional model and for a Widom insertion in a soft sphere liquid, indicating that, with an appropriately chosen bias, conventional methods are in fact more efficient. We describe an analogy between nonequilibrium dynamics and mappings between equilibrium ensembles, which suggests that the practical inferiority of fast switching is quite general. Finally, we discuss the relevance of adiabatic invariants in slowly driven Hamiltonian systems for the application of Jarzynski's theorem.
我们研究了在有限时间内改变控制参数的可逆功计算的最大计算效率。由于相关的非平衡平均值收敛缓慢，对轨迹采样施加偏差可能会有所帮助。然而，这种偏差也可用于计算可逆功的传统方法，如热力学积分或伞形采样。我们给出了一个简单一维模型以及在软球液体中进行维里插入的数值结果，表明通过适当选择偏差，传统方法实际上更有效。我们描述了非平衡动力学与平衡系综之间映射的类比，这表明快速切换在实际中的劣势相当普遍。最后，我们讨论了缓慢驱动的哈密顿系统中的绝热不变量与雅津斯基定理应用的相关性。
