Equilibrium Properties in Classical and Quasiclassical Approximation

Abstract

The justification for including a chapter on classical and quasiclassical approximations into a book devoted to quantum statistics comes from the well known observation that many physical properties of Coulombic systems are determined by classical effects belong, e.g., the equilibrium structure (Baus and Hansen, 1980; Ichimaru, 1982), long-range correlations and screening (Gruber et al., 1980, 1981; Blum et al., 1981, 1982), charge and field fluctuations (Jancovici, 1981, 1982; Lebowitz, 1983) as well as the response behaviour (Golden and Kalman, 1976, 1982). It is not the place here to discuss the classical theory in detail, the interested reader may get some orientation from the references given above, however it seems to be meaningful to explain some basic ideas and to point out the links between the classical and the quantum statistical theory. Therefore we shall concentrate on the question how quantum effects may be included into the classical theories and in what places quantum corrections to the classical behaviour appear.