Discrete dipole models provide a means of calculating optical properties of
semiconductor surfaces rapidly and quite accurately, but they are generall
y regarded as being purely phenomenological. A connection between such mode
ls and a quantum mechanical extreme tight binding (ETB) model is establishe
d here. The dielectric function obtained from an extreme tight binding mode
l is shown to be of similar form to that of a model in which a solid is tre
ated as a lattice of polarizable, pointlike entities, the discrete dipole m
odel. The dielectric matrix is expressed in terms of its eigenvectors and e
igenvalues, which are dipole waves and plasmon energies. The ETB dielectric
matrix is used to derive the self-energy of valence and conduction band st
ates in fee argon. This results in a simple physical picture where intra- a
nd inter-band scattering events result in virtual monopoles and dipoles on
a lattice which couple to plasmon modes. The self-energies of electron and
hole states of fee argon are analysed in terms of multipolar contributions.