CORRELATIONS, COLLISION FREQUENCY AND OPTICAL PROPERTIES IN LASER EXCITED CLUSTERS

Abstract

Within linear response theory, the dielectric and optical properties of a charged particle system are related to equilibrium correlation functions. In particular, the dynamical conductivity and the dynamical collision frequency are expressed in terms of the current-current or force-force correlation function, which can be evaluated analytically using perturbation expansions or numerically by MD simulations. Results are given for bulk material. Furthermore, finite systems such as laser excited clusters are considered. It is shown that the collision frequency is reduced in finite systems. The interaction with the laser field is discussed with respect to the current-current correlation function which changes with time due to the expansion of the laser-irradiated cluster.