Abstract
We report results of calculations of the rotational constants of HCCF recently measured by Holland, Newnham and Mills. We are able to reach, with five parameters, a r.m.s. deviation of ≈5 × 10-4 cm-1 over 76 bands. We also present a study of the Fermi resonances 2ν4 - ν3, 2ν3 - - ν2 and 2ν2 + ν3 - ν1, where we find results similar to those of Mills et al.