Judd-Ofelt theory in a new light on its (almost) 40th anniversary

The standard Judd-Ofelt theory of one photon electric dipole transitions in f(N) systems is discussed in the language of the one particle parametrizat ion scheme. An overview of various physical mechanisms that contribute to t he Judd-Ofelt intensity parameters is performed. The analysis of the morpho logy of these parameters is based on the static model of their original der ivation, dynamic model, electron correlation third order approach, spin-orb it interaction influence, and an exotic perturbation caused by a specific m ass shift. As a new aspect of the investigations on the physical nature of f <---->f transitions, a transformation of the Judd-Ofelt effective operato rs to their relativistic version is presented. In this approach the transit ion amplitude is expressed by the effective double tensor operators, acting within the 4f(N) shell, and effectively representing relativistic contribu tions. In particular, the relativistic form of the crystal field potential is employed, and in addition, the interactions through the crystal held pot ential within the spin-orbital space are included. (C) 2001 Elsevier Scienc e B.V. All rights reserved.