The torsional and asymmetry splittings in HSOH

We refine the analytic treatment developed by Yamada et al. [K.M.T. Yamada, G. Winnewisser, P. Jensen, J. Mol. Struct. 695-696 (2004) 323] to explain the torsional splittings observed for HSOH. Here we find that in addition to the cis- and trans-tunnelling matrix elements, WcandWt, the parameter originating from the torsion-rotation cross-term, ξJ^τJ^z, is also important. The torsional splittings of HSOH have a peculiar nature in that their magnitudes change cyclically with K with a period of approximately three. The previous treatment reproduced one cycle of this variation. Adjusting the three parameters of the current version to experimental data, which now extend to K=5, the calculated splittings reproduce the experimental results quite well. The cyclic pattern is now calculated to extend over at least three cycles.