对称陀螺转子＋线性转子碰撞中转动能量交换的混合量子/经典理论及 $\ m ND_3 + \ m D_2$ 体系案例研究
Mixed Quantum/Classical Theory for Rotational Energy Exchange in Symmetric-Top-Rotor + Linear-Rotor Collisions and a Case Study of $ \rm ND_3 + \rm D_2$ System
Carolin Joy, Bikramaditya Mandal, Dulat Bostan, Dmitri Babikov
备注：
Submitted to journal of Physical Chemistry Chemical Physics
本文扩展MQCT以处理对称陀螺转子＋线性转子碰撞，并以 $\ m ND_3+D_2$ 验证，其态－态截面与全量子结果偏差小于8%，揭示了两步激发机制及两类耦合的作用。
摘要：
本文将用于描述碰撞能量转移的混合量子/经典理论（MQCT）扩展到对称陀螺转子＋线性转子体系类型，并将其应用于 $\ m ND_3 + \ m D_2$。在较宽能量范围内，针对所有可能过程计算了态－态跃迁截面：$\ m ND_3$ 与 $\ m D_2$ 分子同时被激发或同时被淬灭；一个分子被激发而另一个被淬灭，以及相反情形；$\ m ND_3$ 态改变宇称而 $\ m D_2$ 被激发或淬灭；以及 $\ m ND_3$ 被激发或淬灭而 $\ m D_2$ 保持在同一状态（基态或激发态）。在所有这些过程中，MQCT结果均近似满足微观可逆性原理。对于文献中在碰撞能量 $\ m 800 cm^{-1}$ 下给出的16个态－态跃迁集合，MQCT预测的截面值与精确全量子结果相差不超过8%。通过监测MQCT轨迹上态布居的演化，获得了有用的含时认识。结果表明，若碰撞前 $\ m D_2$ 处于基态，则 $\ m ND_3$ 转动态的激发通过两步机制进行：分子－分子碰撞的动能首先用于激发 $\ m D_2$，随后才转移到 $\ m ND_3$ 的激发转动态。研究发现，势能耦合与科里奥利耦合在 $\ m ND_3 + \ m D_2$ 碰撞中均发挥重要作用。
英文摘要：
The extension of mixed quantum/classical theory (MQCT) to describe collisional energy transfer is developed for symmetric-top-rotor + linear-rotor system type and is applied to $ \rm ND_3 + \rm D_2 $. State-to-state transition cross sections are computed in a broad energy range for all possible processes: when both $ \rm ND_3$ and $ \rm D_2$ molecules are excited or both are quenched, when one is excited while the other is quenched and vice versa, when $ \rm ND_3 $ state changes its parity while $ \rm D_2 $ is excited or quenched, and when $ \rm ND_3 $ is excited or quenched while $ \rm D_2 $ remains in the same state, ground or excited. In all these processes the results of MQCT are found to approximately satisfy the principle of microscopic reversibility. For a set of sixteen state-to-state transitions available from literature for collision energy $ \rm 800 cm^{-1} $ the values of cross sections predicted by MQCT are within 8% of accurate full-quantum results. A useful time-dependent insight is obtained by monitoring the evolution of state populations along MQCT trajectories. It is shown that, if before the collision, $ \rm D_2 $ is in its ground state, the excitation of to $ \rm ND_3 $ rotational states proceeds through a two-step mechanism in which the kinetic energy of molecule-molecule collision is first used to excite $ \rm D_2 $ and only then is transferred to the excited rotational states of to $ \rm ND_3 $. It is found that both potential coupling and Coriolis coupling play important roles in $ \rm ND_3 + \rm D_2 $collisions.
Ab initio effective rotational and rovibrational Hamiltonians for non-rigid systems via curvilinear second order vibrational Møller-Plesset perturbation theory
本文提出了一种微扰方法用于刚性和非刚性分子转动和振转有效哈密顿量的从头计算。我们的方法是基于二阶振动Møller-Plesset微扰理论（VMP 2）的曲线实现，通过二阶接触变换扩展到包括旋转效应。虽然更昂贵，这种方法是显着更准确的比标准的二阶振动微扰理论（VPT 2）的系统，很难描述为零阶的直线正常模式谐振子。我们应用这种方法，并证明其准确性的两个分子：硅$_2$ C，一个准线性三原子具有显着的弯曲非谐性，CH $_3$ NO $_2$，其中包含一个完全不受阻碍的甲基转子。除了这两个例子，我们讨论了几个关键的技术方面的方法，包括一个有效的实现Eckart和准Eckart框架嵌入，不依赖于数值有限差分。
Rotational excitation of molecules in the regime of strong ro-vibrational coupling: Comparison between an optical centrifuge and a transform-limited pulse
Universidad de Granada（格拉纳达大学）；The University of British Columbia（不列颠哥伦比亚大学）；Freie Universität Berlin（柏林自由大学）；Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada（格拉纳达大学卡洛斯一世理论与计算物理研究所）
