Schröder Benjamin
Institute of Physical Chemistry, University of Goettingen, Tammannstr. 6, 37077 Göttingen, Germany.
Molecules. 2023 Jul 27;28(15):5700. doi: 10.3390/molecules28155700.
In this work the rovibrational spectrum of the acetylide anion HCC- is investigated using high-level electronic structure methods and variational rovibrational calculations. Using a composite approach the potential energy surface and dipole surface is constructed from explicitly correlated coupled-cluster accounting for corrections due to core-valence correlation, scalar relativistic effects and higher-order excitation effects. Previous approaches for approximating the latter are critically evaluated. Employing the composite potential, accurate spectroscopic parameters determined from variational calculations are presented. In comparison to the few available reference data the present results show excellent agreement with ground state rotational constants within 0.005% of the experimental value. Intensities determined from the variational calculations suggest the bending fundamental transition ν2 around 510 cm-1 to be the best target for detection. The rather weak CD stretching fundamental ν1 in deuterated isotopologues show a second-order resonance with the (0,20,1) state and the consequences are discussed in some detail. The spectroscopic parameters and band intensities provided for a number of vibrational bands in isotopologues of the acetylide anion should facilitate future spectroscopic investigations.
在这项工作中，使用高水平电子结构方法和变分振转计算研究了乙炔化物阴离子HCC⁻的振转光谱。采用复合方法，由显式相关耦合簇构建势能面和偶极面，同时考虑了芯价相关、标量相对论效应和高阶激发效应引起的修正。对先前近似后者的方法进行了批判性评估。利用复合势能，给出了通过变分计算确定的精确光谱参数。与少数可用的参考数据相比，目前的结果与基态转动常数的实验值在0.005%以内显示出极好的一致性。变分计算确定的强度表明，约510 cm⁻¹处的弯曲基频跃迁ν₂是最佳检测目标。氘代同位素中相当弱的CD伸缩基频ν₁与(0,20,1)态呈现二阶共振，并对其结果进行了详细讨论。为乙炔化物阴离子同位素的多个振动带提供的光谱参数和谱带强度应有助于未来的光谱研究。
