  We study the effect of dielectric anisotropy of polymers on their equilibrium
ordering within mean-field theory but with a formalism that takes into account
the full n-body nature of van der Waals forces. Dielectric anisotropy within
polymers is to be expected as the electronic properties of the polymer will
typically be different along the polymer than across its cross section. It is
therefore physically intuitive that larger charge fluctuations can be induced
along the chain than perpendicular to it. We show that this dielectric
anisotropy leads to n-body interactions which can induce an isotropic--nematic
transition. The two body and three body components of the full van der Waals
interaction are extracted and it is shown how the two body term behaves like
the phenomenological self-aligning-pairwise nematic interaction. At the three
body interaction level we see that the nematic phase that is energetically
favorable is discotic, however on the full n-body interaction level we find
that the normal axial nematic phase is always the stable ordered phase. The
n-body nature of our approach also shows that the key parameter driving the
nematic-isotropic transition is the bare persistence length of the polymer
chain.
