In this work we investigate the Renner-Teller effect (RTE) in the photoelectron spectra of ClCN and BrCN. The spectra were calculated by a nuclear wave packet propagation on coupled cationic ${\mathrm{\Pi }}_{1/2}/{\mathrm{\Pi }}_{3/2}$ surfaces obtained by the four-component Fock-space coupled cluster method. The scalar relativistic, spin-orbit and electron correlation effects are consistently included in the hypersurfaces for the three internal nuclear degrees of freedom. In contrast to other approaches no coupling matrix elements involving the spin-orbit operator together with an explicit representation of the wave function were necessary. The current study extends earlier work on the RTE for the derivation of the Renner-Teller parameters c and d where only one nuclear degree of freedom was considered (Pernpointner and Salopiata, 2013). The outlined procedure is especially useful for electronic structure methods that yield accurate energies but do not provide an explicit wave function representation.

在这项工作中，我们研究了ClCN和BrCN的光电子光谱中的Renner-Teller效应（RTE）。通过在耦合阳离子上的核波包传播来计算光谱${\mathrm{\Pi }}_{\mathrm{1个}/\mathrm{2个}}/{\mathrm{\Pi }}_{3/\mathrm{2个}}$通过四分量Fock空间耦合聚类方法获得的曲面。标量相对论，自旋轨道和电子相关效应始终包含在三个内部核自由度的超曲面中。与其他方法相反，不需要包含自旋轨道算子的耦合矩阵元素以及波动函数的显式表示。当前的研究扩展了关于RTE的早期工作，以推导Renner-Teller参数c和d，其中仅考虑了一个核自由度（Pernpointner和Salopiata，2013）。概述的过程对于产生准确能量但不提供明确的波函数表示的电子结构方法特别有用。