New method for the calculation of infra-red intensities

Abstract

A new set of quantities called the “intensity constants”, similar to force constants and defined in terms of dipole moment derivatives, is introduced. A method is outlined for the evaluation of these constants and applied to ethylene. The calculated value of |∂µ/∂r_C—H| agrees with the values reported earlier in the literature. The dipole moment derivatives of formaldehyde and methyl halides are also calculated. The method is free from sign ambiguity and gives unique value for |∂µ/∂r|.