Abstract
Separate sets of force constants for phosphorus trichloride were determined using supplemental molecular information to constrain the general force fields compatible with the vibrational frequencies. The Coriolis zeta constant for the ν4 mode, the centrifugal distortion parameters, and the mean vibrational amplitudes provided convenient sources of additional force‐field information. The agreement among the three final force fields, particularly, for the E symmetry species, confirms the potential function for this molecule.