Use of group theory for the description of electromagnetic scattering from molecular systems

Group theory is applied to the calculation of the multipolar amplitudes of the electromagnetic field scattered by a cluster of spheres, a model scatterer intended to approximate the properties of molecular systems. The multipolar amplitudes are the solution of a system of linear nonhomogeneous equations that group theory allows us to get in factorized form. The consequent computational simplifications improve the reliability of the calculations and allow us to study the scattering even from complex clusters. A few physically significant examples are discussed with particular regard to the dependence of the cross sections on the direction of the incident field.