Wigner Distribution by Adiabatic Switching in Normal Mode or Cartesian Coordinates and Molecular Applications
Wigner Distribution by Adiabatic Switching in Normal Mode or Cartesian Coordinates and Molecular Applications
复制标题
DOI：
10.1021/acs.jctc.8b00179
复制
发表时间：
2018-11-01
影响因子：
5.5
通讯作者：
Makri, Nancy
中科院分区：
文献类型：
--
作者：
Bose, Amartya;Makri, Nancy
最近，我们提出了一个简单的，经典的基于几何的方法，用于生成维格纳相空间密度使用经典的轨迹下演化的电磁开关的潜力。动态切换维格纳（ASW）分布是对精确维格纳函数的近似，它在模型系统上被发现是高度精确的。本文讨论了在简正模坐标系和笛卡尔坐标系下对多原子分子的ASW过程的实现。我们提出了它的应用程序的六度的自由度模型的基础上从头四次势能面开发甲醛在正常模式表示和丁炔在笛卡尔坐标系中使用CHARMM力场。精确的量子力学结果的平衡性质的比较表明，ASW是可靠的，在很宽的温度范围内，在两个坐标系的高度精确。此外，ASW密度在经典演化下是不变的，因此它非常适合于准经典轨道模拟。我们还描述了一个非常简单的ASW为基础的程序获得复值准经典时间相关函数和振动光谱。
We recently presented a simple, classical trajectory-based method for generating the Wigner phase space density using classical trajectories evolving under an adiabatically switched potential. The adiabatically switched Wigner (ASW) distribution is an approximation to the exact Wigner function, which was found to be highly accurate on model systems. In this paper we discuss the implementation of the ASW procedure to polyatomic molecules both in normal mode coordinates and in Cartesian coordinates. We present its application to a six-degree-of-freedom model based on an ab initio quartic potential energy surface developed for formaldehyde in the normal mode representation and for butyne in Cartesian coordinates using the CHARMM force field. Comparisons of equilibrium properties against accurate quantum mechanical results indicate that the ASW is reliable and highly accurate over a wide temperature range in both the coordinate systems. Further, the ASW density is invariant under classical evolution, thus it is ideally suited to quasiclassical trajectory simulations. We also describe a very simple ASW-based procedure for obtaining complex-valued quasiclassical time correlation functions and vibrational spectra.