Influence of kinetic coupling in rectilinear coordinates on the vibrational spectrum of fluoroform

The vibrational energy levels of fluoroform have been computed with and without the kinetic coupling terms of the Eckart–Watson Hamiltonian by using the vibrational mean field configuration interaction method. The results are well-converged as demonstrated by a comparison with those obtained with other variational methods when kinetic coupling is omitted. It is found that kinetic coupling is not negligible for this system. The wave number difference with and without kinetic coupling is 37 cm−1 for the ν 1 (CH-stretching) fundamental transition and can be larger than 60 cm−1 in the ν 1 – ν 4 (HCF bending) overtones.