Large amplitude quantum mechanics in polyatomic hydrides. I. A particles-on-a-sphere model for XH(n).
Large amplitude quantum mechanics in polyatomic hydrides. I. A particles-on-a-sphere model for XH(n).
复制标题
多原子氢化物中的大振幅量子力学。
DOI：
10.1063/1.1940613
复制
发表时间：
2005
期刊：
影响因子：
--
通讯作者：
D. Nesbitt
中科院分区：
文献类型：
--
作者：
Michael P Deskevich;D. Nesbitt
提出了一个基于相对简单但计算易于处理的轻原子分子内运动“球体粒子”（POS）模型的多原子氢化物（XH（n））大振幅动力学的聚合量子力学计算框架。该模型假设嵌入球体表面的 H 原子具有任意原子间角势的独立二维 (2D) 角运动。这一假设允许系统演化，从“自由转子”到“隧道”再到“准刚性”多原子分子行为，以获得小但有限的总角动量 J 值。这项工作重点关注简单的三原子 (n=2) 和四原子 (n=3) 系统作为原子间势刚度的函数，并明确考虑 H2O、NH3 和 H3O+ 作为限制测试用例。 POS 模型还为动态计算更具挑战性的 XH(n) 物种（n>3）（例如 CH5+ 模型）建立了必要的数学基础，其中这种降维方法为超音速射流膨胀条件的低 J 值（即 J=0, 1, 2）特征下的量子力学可处理提供了前景。
A framework is presented for converged quantum mechanical calculations on large amplitude dynamics in polyatomic hydrides (XH(n)) based on a relatively simple, but computationally tractable, "particles-on-a-sphere" (POS) model for the intramolecular motion of the light atoms. The model assumes independent two-dimensional (2D) angular motion of H atoms imbedded on the surface of a sphere with an arbitrary interatomic angular potential. This assumption permits systematic evolution from "free rotor" to "tunneling" to "quasi-rigid" polyatomic molecule behavior for small, but finite, values of total angular momentum J. This work focuses on simple triatom (n=2) and tetratom (n=3) systems as a function of interatomic potential stiffness, with explicit consideration of H2O, NH3, and H3O+ as limiting test cases. The POS model also establishes the necessary mathematical groundwork for calculations on dynamically much more challenging XH(n) species with n>3 (e.g., models of CH5+) where such a reduced dimensionality approach offers prospects for being quantum mechanically tractable at low J values (i.e., J=0, 1, 2) characteristic of supersonic jet expansion conditions.