Abstract
The general sextic force field of carbon dioxide has been determined by matrix diagonalization (A, table 1). Comparison with previous force fields derived by the application of perturbation theory and contact transformation suggests that it represents the potential surface in the 0–11 000 cm-1 range to about 1 per cent. Of the three approaches, contact transformation has been found to be more accurate in its prediction of band centres and rotational and centrifugal distortion constants.