  The synergy between high-resolution rotational spectroscopy and
quantum-chemical calculations is essential for exploring future detection of
molecules, especially when spectroscopy parameters are not available yet. By
using highly correlated ab initio quartic force fields (QFFs) from explicitly
correlated coupled cluster theory, a complete set of rotational constants and
centrifugal distortion constants for D$_2$CS and cis/trans-DCSD isomers have
been produced. Comparing our new ab initio results for D$_2$CS with new
rotational spectroscopy laboratory data for the same species, the accuracy of
the computed B and C rotational constants is within 0.1% while the A constant
is only slightly higher. Additionally, quantum chemical vibrational frequencies
are also provided, and these spectral reference data and new experimental
rotational lines will provide additional references for potential observation
of these deuterated sulfur species with either ground-based radio telescopes or
space-based infrared observatories.
