The r-centroid approximation and molecular spectra

An exteusive computational study bad been made over a wide range of molecular constants for representative 'model' diatomic oxides, nitrides, chlorides, fluorides, hydrides and deuterides of the degree of approximation involved in the use of the r-centroid concept of the interpretation of intensities of molecular spectra. It was found that the approximation is good to better than a few percent (often one percent) in all cases except for hydrides and deuterides.