Department of Chemistry, University of Waterloo, Waterloo, Canada, Ontario N2L 3G1.
J Chem Phys. 2012 Jun 14;136(22):224309. doi: 10.1063/1.4726507.
We present an implementation of path integral molecular dynamics for sampling low temperature properties of doped helium clusters using Langevin dynamics. The robustness of the path integral Langevin equation and white-noise Langevin equation [M. Ceriotti, M. Parrinello, T. E. Markland, and D. E. Manolopoulos, J. Chem. Phys. 133, 124104 (2010)] sampling methods are considered for those weakly bound systems with comparison to path integral Monte Carlo (PIMC) in terms of efficiency and accuracy. Using these techniques, convergence studies are performed to confirm the systematic error reduction introduced by increasing the number of discretization steps of the path integral. We comment on the structural and energetic evolution of He(N)-CO(2) clusters from N = 1 to 20. To quantify the importance of both rotations and exchange in our simulations, we present a chemical potential and calculated band origin shifts as a function of cluster size utilizing PIMC sampling that includes these effects. This work also serves to showcase the implementation of path integral simulation techniques within the molecular modelling toolkit [K. Hinsen, J. Comp. Chem. 21, 79 (2000)], an open-source molecular simulation package.
我们提出了一种路径积分分子动力学的实现方法，用于使用朗之万动力学对掺杂氦团簇的低温性质进行采样。路径积分朗之万方程和白噪声朗之万方程[M. Ceriotti、M. Parrinello、T. E. Markland 和 D. E. Manolopoulos，J. Chem. Phys. 133，124104（2010）]采样方法的稳健性被考虑用于那些弱结合系统，并与路径积分蒙特卡罗（PIMC）在效率和准确性方面进行了比较。使用这些技术，进行了收敛性研究，以确认通过增加路径积分的离散化步骤数量引入的系统误差减少。我们对 He(N)-CO(2) 团簇从 N = 1 到 20 的结构和能量演化进行了评论。为了量化我们模拟中旋转和交换的重要性，我们提出了一个化学势，并计算了作为簇大小函数的带隙起源位移，利用包括这些效应的 PIMC 采样。这项工作还展示了路径积分模拟技术在分子建模工具包[K. Hinsen，J. Comp. Chem. 21，79（2000）]中的实现，这是一个开源的分子模拟包。
