Local response model of the generalized polarization potential

Abstract

An electron scattered by an atom or molecule experiences a generalized polarization potential due to bound-free correlation. A classical electrostatic model of this correlation potential is presented that is equivalent to a local-density response model recently used to compute van der Waals interaction constants. The frequency-dependent oscillator strength is parametrized as a function of local electron density for each volume element in an extended electronic system, atom, or molecule. A response surface is defined by a cutoff criterion that can be chosen for atoms to give the empirical static dipole polarizability. The classical model extends this theory to arbitrary geometry and to shorter-range interactions. A density-dependent dielectric constant is defined within the response surface. This model determines the polarization response and internal electric field due to an external test charge, as well as the generalized polarization potential acting on the test charge. © 1997 The American Physical Society.