Bond charge parameters from integrated infrared intensities

A procedure is outlined to analyze the infrared absorption intensities of fundamental vibration bands in terms of “bond charge parameters”. The method is illustrated for some small C_2v- and C_3v-type molecules: SO₂, NF₃, and PF₃. The values obtained for the “bond charge reorganizations” and “effective bond charges” for SO, NF, and PF bonds are discussed. The method offers the possibility of calculating rotational contributions without the use of a reference molecule.