Benchmark variational calculations of the Born–Oppenheimer potential energy curve (PEC) performed with explicitly correlated all-electron Gaussian functions with shifted centers are presented. The PEC energies include the leading relativistic and quantum-electrodynamics corrections and the first-order corrections due to adiabatic effects. The PEC is used to calculate the ro-vibrational spectra for HeH − and its isotopologues. The results show that these systems are marginally stable and have two to four bound vibrational levels and, for each vibrational level, a few bound rotational levels lying below the dissociation threshold. This indicates a possibility of detecting the HeH − anion in the laboratory and, perhaps, even in the interstellar space.

中文翻译：

---

HeH-及其同同位素的旋振谱的基准计算

提出了Born-Oppenheimer势能曲线（PEC）的基准变分计算，该计算使用了明显相关的具有移位中心的全电子高斯函数。PEC能量包括领先的相对论和量子电动力学校正以及由于绝热效应引起的一阶校正。PEC用于计算HeH-及其同同位素的旋转振动光谱。结果表明，这些系统是边缘稳定的，具有2-4个约束振动级，并且对于每个振动级，有几个约束旋转级位于解离阈值以下。这表明有可能在实验室甚至在星际空间中检测到HeH-阴离子。