Radium compounds have attracted recently considerable attention due to both development of experimental techniques for high-precision laser spectroscopy of molecules with short-lived nuclei and amenability of certain radium compounds for direct cooling with lasers. Currently, radium monofluoride (RaF) is one of the most studied molecules among the radium compounds, both theoretically and recently also experimentally. Complementary studies of further diatomic radium derivatives are highly desired to assess the influence of chemical substitution on diverse molecular parameters, especially on those connected with laser cooling, such as vibronic transition probabilities, and those related to violations of fundamental symmetries. In this article high-precision ab initio studies of electronic and vibronic levels of diatomic radium monochloride (RaCl) are presented. Recently developed approaches for treating electronic correlation with Fock-space coupled cluster methods are applied for this purpose. Theoretical results are compared to an early experimental investigation by Lagerqvist and used to partially reassign the experimentally observed transitions and molecular electronic levels of RaCl. Effective constants of $\mathcal{P}$-odd hyperfine interaction $W_{\mathrm{a}}$ and $\mathcal{P},\mathcal{T}$-odd scalar-pseudoscalar nucleus-electron interaction $W_{\mathrm{s}}$ in the ground electronic state of RaCl are estimated within the framework of a quasirelativistic Zeroth-Order Regular Approximation approach and compared to parameters in RaF and RaOH.

由于对具有短寿命原子核的分子进行高精度激光光谱的实验技术的发展以及对某些镭化合物可通过激光直接冷却的适应性，镭化合物最近引起了相当大的关注。目前，从理论上和最近在实验上，一氟化镭（RaF）都是镭化合物中研究最多的分子之一。迫切需要对其他双原子镭衍生物进行补充研究，以评估化学取代对各种分子参数的影响，尤其是对与激光冷却有关的那些参数，如电子振动跃迁几率以及与违反基本对称性有关的那些参数。本文中的高精度从头算提出了对双原子一氯化镭（RaCl）的电子和振动水平的研究。为此目的，采用了最近开发的利用福克空间耦合聚类方法处理电子相关性的方法。理论结果与Lagerqvist的早期实验研究进行了比较，并用于部分重新分配实验观察到的RaCl的跃迁和分子电子能级。有效常数$\mathcal{P}$奇数超精细相互作用 ${\mathrm{w\; ^}}_{\mathrm{一个}}$ 和 $\mathcal{P}，\mathcal{Ť}$奇数标量-伪标量核-电子相互作用 ${\mathrm{w\; ^}}_{\mathrm{s}}$ RaCl的基态电子态是在拟似实的零阶正则逼近方法框架内估算的，并与RaF和RaOH中的参数进行比较。