Calculation of the mean polarizability derivatives of hydrocarbon molecules

The mean polarizability derivatives of CH 4 , C 2 H 2 , C 2 H 4 and C 2 H 6 are calculated through a variational procedure. Satisfactory numerical results are obtained using the CNDO approximation with polarization functions included in the basis set. The frequency dependence of the means polarizability derivative is examined, and the separate contributions from σ and π electrons are calculated for the ethylene molecule.