Joubert-Doriol Loïc, Sivasubramanium Janakan, Ryabinkin Ilya G, Izmaylov Artur F
Department of Physical and Environmental Sciences, University of Toronto Scarborough , Toronto, Ontario M1C 1A4, Canada.
Chemical Physics Theory Group, Department of Chemistry, University of Toronto , Toronto, Ontario M5S 3H6, Canada.
J Phys Chem Lett. 2017 Jan 19;8(2):452-456. doi: 10.1021/acs.jpclett.6b02660. Epub 2017 Jan 6.
On-the-fly quantum nonadiabatic dynamics for large systems greatly benefits from the adiabatic representation readily available from electronic structure programs. However, conical intersections frequently occurring in this representation introduce nontrivial geometric or Berry phases which require a special treatment for adequate modeling of the nuclear dynamics. We analyze two approaches for nonadiabatic dynamics using the time-dependent variational principle and the adiabatic representation. The first approach employs adiabatic electronic functions with global parametric dependence on the nuclear coordinates. The second approach uses adiabatic electronic functions obtained only at the centers of moving localized nuclear basis functions (e.g., frozen-width Gaussians). Unless a gauge transformation is used to enforce single-valued boundary conditions, the first approach fails to capture the geometric phase. In contrast, the second approach accounts for the geometric phase naturally because of the absence of the global nuclear coordinate dependence in the electronic functions.
对于大型系统的实时量子非绝热动力学，能从电子结构程序中轻松获得的绝热表示中受益匪浅。然而，这种表示中频繁出现的锥形交叉会引入非平凡的几何或贝里相位，这需要特殊处理才能对核动力学进行充分建模。我们使用含时变分原理和绝热表示来分析两种非绝热动力学方法。第一种方法采用对核坐标具有全局参数依赖性的绝热电子函数。第二种方法使用仅在移动的局域化核基函数中心（例如，固定宽度的高斯函数）处获得的绝热电子函数。除非使用规范变换来强制单值边界条件，否则第一种方法无法捕捉几何相位。相比之下，第二种方法由于电子函数中不存在对全局核坐标的依赖性，自然地考虑了几何相位。
