Spectroscopic Investigation of Thioacrolein by Variational and Perturbational Approaches

The vibrational spectra of trans and cis-thioacrolein have been studied by 2nd order vibrational perturbation theory (VPT2) and vibrational configuration interaction (VCI) theory. All calculations rely on multilevel potential energy surfaces (PESs) with the highest level being explicitly correlated coupled-cluster theory including single and double excitation and a perturbational treatment of the triple excitation in combination with an augmented triple- ζ basis set. Comparisons with experimental data are provided, including a number of predictions for unobserved fundamentals. Moreover, (ro) vibrational configuration interaction (RVCI) theory has been used for the simulation of the microwave spectrum, accompanied by the calculation of spectroscopic constants from perturbation theory.