The General Harmonic Force Field of Methyl Chloride

The complete general harmonic force field of methyl chloride has been recalculated using the most recent literature frequency, Coriolis zeta, and centrifugal distortion data for (12)CH(3)(35)Cl, (13)CH(3)(35)Cl, (12)CD(3)(35)Cl, (12)CHD(2)(35)Cl, (12)CH(2)D(35)Cl, (12)CH(3)(37)Cl, (12)CD(3)(37)Cl, (12)CHD(2)(37)Cl, (12)CH(2)D(37)Cl, and (13)CH(3)(37)Cl. The anharmonic corrections applied to the observed frequency data are considered to be more realistic than those used hitherto. There is excellent agreement between the fitted force constants and literature high-quality ab initio force fields. The results of the least-squares refinement of the full-harmonic force field is compared with least-squares refinement of only the scale factors for an SCF calculated force field since the latter approach may be useful for larger molecules where more sophisticated calculations are impractical. The results of a refinement of only the scale factors for an MP4 calculated force field are also reported. Copyright 2001 Academic Press.