Vibrational energy levels of methyl chloride calculated from full dimensional ab initio potential energy surface

The vibrational levels for two isotopic species of methyl chloride have been calculated in the region 0-3500 cm⁻¹ from the ab initio potential energy surface (PES). The isotopic shift of vibrational levels of molecules ¹²CH₃³⁵Cl and ¹²CH₃³⁷Cl has been calculated. The correlation consistent basis sets cc-pVTZ and cc-pVQZ are employed to calculate energy values for 7957 and 3758 points correspondingly from a large domain of the nine-dimensional internal coordinate space. The analytic global PES is fitted with the standard deviation of 4.5 cm⁻¹.