Transition frequencies were taken from
(1) M. C. McCarthy, K. L. K. Lee, P. B. Carroll, J. P. Porterfield, P. B. Changala, J. H. Thorpe, and J. F. Stanton, 2020, J. Phys. Chem. A 124, 5170.
The uncertainties were deemed too conservative and were adjusted from 2 to 1 kHz. Initial estimates of the quartic distortion parameters were taken from a B3LYP quantum-chemical calculation by
(2) H. S. P. Müller, 2022, unpublished;
the final parameter set differs somewhat from that in (1).
The data set is very limited. The calculations were therefore truncated at 54 GHz and at J = 29. The calculations should be sufficient for searches in cold environments. Transition frequencies with calculated uncertainties exceeding 0.1 MHz should be viewed with caution.
The dipole moment is from a quantum-chemical calculation by
(3) K. L. K. Lee and M. C. McCarthy, 2019, J. Phys. Chem. Lett. 10, 2408.