论文标题
高准确性RB $ _ {2}^+$基于耦合群集计算
High-accuracy Rb$_{2}^+$ interaction potentials based on coupled cluster calculations
论文作者
论文摘要
这项工作讨论了一个协议，用于为最低的两个状态构建高度准确的势能曲线（PEC），即$ _ {2}^+$，即$ x \，{}^2σ{_g^+} $和$（1）{}^2σ{}^2σ{_U^+} $，使用基于加法方案的理论。该方法利用了我们先前工作的发现[J. Schnabel，L。Cheng和A.Köhn，J。Chem。物理。 155，124101（2021）]为了避免使用高阶群集操作员的扰动估计值时，对称分子离子发生的非物理排斥性远程屏障。此外，还要注意$ x {}^2σ{_g^+} $和$（1）{}^2σ{_u^+} $ pecs的物理正确交换分裂。我们的计算方法的准确性是为RB和光谱常数电离能以及$ a {}^3σ{_u^+} $ rb \ textSubscript {2}的振动水平的基准测试。我们研究了高级相关贡献，高级相对论效应和内壳相关性贡献，并在$ a \，{}^3σ{_u^3σ{_u^+} $ thinep $ a \ a \ a \ a \ a \ a \ a \ a \ a \ a \ a \ a \ a \ a \ a \ a \ a \^+} $ trine的实验参考值中找到了非常吻合的一致性。我们对RB $ _ {2}^+$ $ x {}^2σ{_g^+} $状态的最终最佳估计值，包括零点振动贡献为$ d_0 = 6179 \，\ Mathrm {cm} 30 \，\ mathrm {cm}^{ - 1}）$。该值小于$ d_0 \ ge 6307.5 \，\ mathrm {cm}^{ - 1} $ [Bellos等人，物理学的实验推断的下键。 Rev. A 87，012508（2013）]，需要进一步调查。对于$（1）{}^2σ{_U^+} $状态浅势，带有$ d_0 = 78.4 \，\ Mathrm {cm}^{ - 1} $，$ \ pm 9 \，\ pm 9 \，\ mathrm {cm}^{cm}^{ - 1} $的错误绑定。
This work discusses a protocol for constructing highly accurate potential energy curves (PECs) for the lowest two states of Rb$_{2}^+$, i.e. $X\,{}^2Σ{_g^+}$ and $(1) {}^2Σ{_u^+}$, using an additivity scheme based on coupled-cluster theory. The approach exploits the findings of our previous work [J. Schnabel, L. Cheng and A. Köhn, J. Chem. Phys. 155, 124101 (2021)] to avoid the unphysical repulsive long-range barrier occurring for symmetric molecular ions when perturbative estimates of higher-order cluster operators are employed. Furthermore, care was taken to reproduce the physically correct exchange splitting of the $X {}^2Σ{_g^+}$ and $(1) {}^2Σ{_u^+}$ PECs. The accuracy of our computational approach is benchmarked for ionization energies of Rb and for spectroscopic constants as well as vibrational levels of the $a {}^3Σ{_u^+}$ triplet state of Rb\textsubscript{2}. We study high-level correlation contributions, high-level relativistic effects and inner-shell correlation contributions and find very good agreement with experimental reference values for the atomic ionization potential and the binding energy of Rb$_{2}$ in the $a\,{}^3Σ{_u^+}$ triplet state. Our final best estimate for the binding energy of the Rb$_{2}^+$ $X {}^2Σ{_g^+}$ state including zero-point vibrational contributions is $D_0 = 6179\,\mathrm{cm}^{-1}$ with an estimated error bound of $\mathcal{O}(\pm 30\,\mathrm{cm}^{-1})$. This value is smaller than the experimentally inferred lower bond of $D_0\ge 6307.5\,\mathrm{cm}^{-1}$ [Bellos et al., Phys. Rev. A 87, 012508 (2013)] and will require further investigation. For the $(1) {}^2Σ{_u^+}$ state a shallow potential with $D_0 = 78.4\,\mathrm{cm}^{-1}$ and an error bound of $\pm 9\,\mathrm{cm}^{-1}$ is computed.
