Department of Chemistry, University of Nebraska-Lincoln, 433 Hamilton Hall, Lincoln, Nebraska 68588-0304, USA.
Chemistry Department, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Kingdom of Saudi Arabia.
J Chem Phys. 2018 Aug 14;149(6):064304. doi: 10.1063/1.5040141.
Carbon disulfide is a prototype molecular system for studies of photophysical processes in molecules at different time scales and is also relevant to astrophysics. Here, reliable molecular properties are computed for linear SCS, bent CS, and linear CSS forms using highly correlated post Hartree-Fock methods in conjunction with large basis sets. Structures are identified using explicitly correlated and standard coupled cluster techniques. Evolution of the lowest-lying singlet and triplet electronic states of the three isomers along the SS and CS stretching coordinates and along the bending angle are mapped at the multireference configuration interaction (MRCI)/aug-cc-pV(5+d)Z level of theory. The computations suggest that the B(Σ) electronic state of the SCS isomer plays an important role in the photoconversion of CS to -CS and CSS. Photoconversion competes with photodissociation. Plausible mechanisms for the production of S and CS diatomics after the photoexcitation of SCS are proposed. To aid in the identification of CSS in the laboratory and in astrophysical media, a set of spectroscopic constants and rovibrational levels for CSS are reported.
二硫化碳是研究分子在不同时间尺度上光物理过程的典型分子体系，也与天体物理学有关。在这里，使用高度相关的后哈特利-福克方法和大型基组，为线性 SCS、弯曲 CS 和线性 CSS 形式计算了可靠的分子性质。使用显式相关和标准耦合簇技术来确定结构。在多参考组态相互作用（MRCI）/aug-cc-pV（5+d）Z 理论水平上，沿着 SS 和 CS 伸缩坐标以及弯曲角度，对三种异构体的最低单重态和三重态电子态的演化进行了映射。计算表明，SCS 异构体的 B（Σ）电子态在 CS 向 -CS 和 CSS 的光转化中起着重要作用。光转化与光解离竞争。提出了 SCS 光激发后产生 S 和 CS 双原子的可能机制。为了帮助在实验室和天体物理介质中识别 CSS，报告了一组 CSS 的光谱常数和振转能级。
