Computational Science, Department of Chemistry and Applied Biosciences, ETH Zürich, Lugano, Switzerland.
J Chem Phys. 2011 Feb 28;134(8):084104. doi: 10.1063/1.3556661.
The quantum nature of nuclei plays an important role in the accurate modelling of light atoms such as hydrogen, but it is often neglected in simulations due to the high computational overhead involved. It has recently been shown that zero-point energy effects can be included comparatively cheaply in simulations of harmonic and quasiharmonic systems by augmenting classical molecular dynamics with a generalized Langevin equation (GLE). Here we describe how a similar approach can be used to accelerate the convergence of path integral (PI) molecular dynamics to the exact quantum mechanical result in more strongly anharmonic systems exhibiting both zero point energy and tunnelling effects. The resulting PI-GLE method is illustrated with applications to a double-well tunnelling problem and to liquid water.
原子核的量子性质在精确模拟轻原子（如氢）方面发挥着重要作用，但由于涉及到高计算开销，在模拟中通常被忽略。最近的研究表明，通过在经典分子动力学中增加广义朗之万方程（GLE），可以相对廉价地在谐波和准谐波系统的模拟中包含零点能效应。本文描述了如何使用类似的方法来加速路径积分（PI）分子动力学在更强烈非谐系统中的收敛速度，该系统同时表现出零点能和隧穿效应。所得到的 PI-GLE 方法通过应用于双势阱隧穿问题和液态水进行了说明。
