Interactions in polar media. I. Interparticle interaction energy

Abstract

Using permanent plus induced charge distributions on particles a Hartree method is used to compute the polar contribution to the interparticle interaction energy. Each particle may be a single molecule or a collection of molecules, a whole electrode or an entire medium for example. The total interparticle interaction energy is taken to be the sum of this polar term and of an interparticle electron correlation term. The second of these includes effects due to interparticle London dispersion and exchange repulsion forces. A symmetry property associated with a quantum mechanical operator characterizing the induced charge distribution is obtained in a compact way using a projection operator. The polar term is also calculated from classical electrostatics and shown to be the same as the one above. The present work is a generalization of earlier treatments in which the particles were single molecules interacting via permanent and induced dipoles.An application of this work is the more general formulation of theories associated with polar interactions in condensed phases, such as the theory of electron transfer rates in solution and at electrodes, and the theory of electronic spectral shifts and band broadening of polar solutes in polar media.