Wigner scattering theory for systems held together by Coulombic forces

The relevance of Wigner Scattering theory and in particular of its K-matrix formulation is stressed for all systems held together by Coulombic forces including not only atoms and molecules but also clusters. Originally developed and formulated for nuclear scattering, Wigner’s theory is extremely general, with application in many branches of physics. Atomic Physics often makes use of an apparently separate formalism (MQDT) which is in fact a specialisation of Wigner’s theory. The advantage of the K-matrix is that analytic expressions can be given for interactions between resonances in terms of a meromorphic pole structure in the special case of asymptotically Coulombic potentials. By using the K-matrix, a number of novel effects (q-reversals, vanishing radiative and particle widths, vanishing fluctuations, etc.) are understood as general phenomena