a1 Johns Hopkins University, Baltimore
The analysis of the interactions between the electrons of different atoms is complicated by many effects. Unless the atoms are free and well separated, account has to be taken of covalency, overlap, exchange, and superexchange. But, although such effects are often important, it is sometimes useful to regard the electrons as being located on separate atoms. Two electrons, labelled 1 and 2, on respective atoms A and B, then interact principally through the Coulomb energy e2/r12. Neighbouring atoms L, M, N, …, which we suppose are spherically symmetric, make their presence felt by acting as polarizable spheres. The electric fields thereby produced modify the simple Coulombic expression for the energy of interaction of the two electrons. It is the purpose of this article to examine such modifications in detail.
(Received October 24 1975)