The anharmonic force field of carbon disulphide

The anharmonic force field for carbon disulphide has been determined by matrix diagonalization. Changes in the potential surface, owing to the modification of the data set used in its calculation and comparison with previous work based on perturbation theory, indicates that the present field (C, table 1) describes the potential surface in the 0–5500 cm-1 region to better than 1 per cent. Employing the ρ expansion coordinate, rather than the more common я variable, is found to be a useful method of reducing the number of force field parameters, while retaining an adequate description of the potential surface.