Electrostatic model for infrared intensities in a spectroscopically determined molecular mechanics force field

A new electrostatic model for the calculation of infrared intensities in molecular mechanics and molecular dynamics is presented. The model is based on atomic charges, atomic charge fluxes, and internal coordinate dipoles and their fluxes. The internal coordinate dipoles are used instead of atomic dipoles, thus simplifying the derivation of parameters. The model is designed to reproduce ab initio dipole derivatives, and the parameters can be obtained by Ž . iterative transformations from these, or by linear least squares fitting to them. A first application to linear alkanes has been made. For these molecules, the intensities can be predicted with an average accuracy of 30]40%. Q 1998 John Wiley & Sons, Inc. J Comput Chem 19: 754]768, 1998