Information on the atom jump processes during the establishment and destruction of long-range order can be gained from measurement of residual electrical resistivity ( REST). By its nature this very sensitive method yields an integral signal, so theoretical efforts are mandatory to properly understand how the single atom jumps work together in generating it. As a valuable approach we report on Monte Carlo simulations of atom kinetics which process the individual jumps into macroscopic configurational changes. In order to create a more reliable quantitative basis for individual jump frequencies we propose ab initio calculations of defect energies and migration profiles, a method which has become increasingly accessible in recent years. When experimental investigation is enlightened by combining these two theoretical methods, we expect deep insight into the hierarchy of atomic movement during changes of the ordered state. First steps towards such an ideal program are discussed. An outlook is given how the theoretical methods described offer structural and kinetic information on various scales and in different systems. (C) 2004 Kluwer Academic Publishers.