Atom Dipole Interaction Model ADIM

The atom dipole interactioii model has been proposed by Silberstein [320] and revived in the beginning of the 1970 s by Applequist, Carl and Fung [289], Later ADIM has been further developed and applied in solving different spectroscopic problems [321-329], 

The atom dipole interaction model is an alternative expression of the additive approximation for vibrational intensities. It is based on the assumption that the molecular polarizability is a sum of polarizabilities of the constituent atoms. The interactions between atoms in the molecule are realized by the electromagnetic fields of induced atomic dipoles. 

An isotropic polarizability Oj centered at die nucleus is assigned to each atom i of an N-atomic molecule. When an external electric field fj is applied to atom i, an induced dipole ii is created [289] 

Ty is the induced dipole field tensor and pg and (g = 1 to N) are column vectors. The last term in Eq. (9.54) accounts for the contribution of the induced dipole fields to die overall field strength. In explicit form die dipole field tensor Ty is given by [289] 

In this equation ry is the length of a vector pointing fiom atom i towards atom j, and x, y and z are the respective vector components in a molecule-fixed Cartesian coordinate system. Expressions analogous to Eq. (9.55) can be written for each atom of the molecule. Thus, after rearranging the components of Eq. (9.54), the following set of N matrix equations is obtained 

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