Dithioformic acid occurs in two conformers, the lower energy trans conformer and the cis conformer, which is about 500 K (or 350 cm^–1) higher in energy. The experimental transition frequencies were summarized in
(1) D. Prudenzano, J. Laas, L. Bizzocchi, V. Lattanzi, C. Endres, B. M. Giuliano, S. Spezzano, M. E. Palumbo, and P. Caselli, 2018 Astron. Astrophys. 612, Art. No. A56.
A modest number of transition frequencies were taken from
(2) B. Bak, O. J. Nielsen, H. Svanholt, 1978 J. Mol. Spectrosc. 69, 401.
The energy difference was determined in (2).
Predicted transition frequencies should be sufficient for all observational purposes, but should be viewed with caution if the uncertainties exceed 0.3 MHz.
The partition functions takes into consideration only the ground vibrational states of both conformers. Individual contributions are available. Vibrational correction factors should be available in the future.
The ab initio dipole moment components were reported in (1). The a components are in good agreement with experimental values in (2).