The study of long-range interactions is increasingly becoming essential due to its various applications in cold atomic physics. These interactions can be conveniently expressed in terms of dispersion coefficients. In the present work, theoretical calculations have been carried out to estimate the two-dipole ($C_6$) and three-dipole ($C_9$) dispersion coefficients between the group XII atoms and their ions, \textit{viz.}, Zn, Cd, Hg, Zn$^+$, Cd$^+$, and Hg$^+$. To obtain these coefficients, the dynamic dipole polarizabilities and reduced matrix elements required are evaluated using the relativistic methods for both the considered atoms and ions. Further, using the calculated matrix elements, the oscillator strengths corresponding to leading transitions and static dipole polarizabilities are determined. These are compared with the available values in the literature through which the accuracy of the present calculations ascertains. However, the oscillator strengths for few transitions of Zn, Cd, Hg, Zn$^+$, Cd$^+$, and Hg$^+$, are not reported earlier, and we have provided their values in this work. Thereafter, the dispersion $C_6$ and $C_9$ coefficients are calculated for various combinations of the group XII elements, and most of these coefficients were not reported earlier in the literature. Furthermore, the combinations for which the other theoretical and experimental values were available for comparison showed good agreement. We, therefore, believe that our results reported for $C_6$ and $C_9$ coefficients for various combinations of group XII elements are reliable.
Multipole-moment effects in ion-molecule reactions at low temperatures: part I -- Ion-dipole enhancement of the rate coefficients of the He$^+$ + NH$_3$ and He$^+$ + ND$_3$ reactions at collision energies near $0$ K
He $^+$和氨（NY $_3$，Y= {H，D}）之间的反应速率的能量依赖性，形成NY $_2^+$，Y和He以及NY $^+$，Y $_2$和He，以及相应的产物分支比已经使用最近开发的合并束技术在0和$k_{\mathrm{B}}\cdot40$ K之间的低碰撞能量下测量[Allmendinger { \it et al.}，ChemPhysChem { \bf 17}，3596（2016）]。为了避免杂散电场对离子的加热，在高激发态里德堡电子的大轨道内观察反应。使用曲面电极里德堡-斯塔克偏转器将He里德堡原子束与超音速氨束合并，该偏转器也用于调节He里德堡原子的最终速度，从而调节碰撞能量（$E_{\rm coll}$）。在最低的$E_{\rm coll}$值下，达到了约200 mK的碰撞能量分辨率。的反应速率系数表现出急剧增加的碰撞能量低于$\sim k_{\mathrm{B}}\cdot5$ K和明显偏离Langevin捕获行为。实验结果解释的绝热捕获模型描述的旋转状态依赖的取向的氨分子的He $^+$原子的电场。该模型忠实地描述了实验观察。在最低碰撞能量下观察到的两种反应的反应产率的提高归因于在低电场下经历线性斯塔克位移的高场寻求状态。从该模型导出了与天体化学有关的0 ~ 10~K温度范围内的热俘获速率常数。计算的热捕获速率系数与Marquette { \it et …
A Comparative Analysis of Non-relativistic and Relativistic Calculations of Electric Dipole Moments and Polarizabilities of Heteronuclear Alkali Dimers
