  A numerical program calculating an energy of a positron or (and) an electron
near the free volume in solid n-alkanes has been build. The theory of
interaction of e+ or (and) e- with this non-polar media based on polarizability
has been introduced. The energy of the e+ -- e- pair in the bulk was compared
to that calculated when the pair forms a positronium (Ps) inside the free
volume. The calculations are based on the Coupled Dipole Method and the
dipole-dipole interaction energy for induced dipoles is taken into account.
Furthermore, a correction of a local permittivity for the e+ -- e- interaction
is calculated taking into account the non-isotropic medium between them. The
method is a step toward more accurate calculations of energetic conditions
during the Ps formation in matter. The possibility of emission of the excess
energy of the Ps formation as electromagnetic radiation is discussed. It is
argued that if this radiation is observed, it can be used as a new
spectroscopic tool providing information about microscopic properties of media.
