  The lattice field theory approach to the statistical mechanics of a classical
Coulomb gas [R. Coalson and A. Duncan, J. Chem. Phys. 97,5653(1992)] is
generalized to include charged polymer chains. Saddle-point analysis is done on
the functional integral representing the partition function of the full system.
Mean-field level analysis requires extremization of a real-valued functional
with a single minimum, thus guaranteeing a unique solution. The full mean-field
equations for such a coupled system are derived, as well as the leading
(one-loop) fluctuation corrections. Two different numerical real-space lattice
procedures are developed to implement the generalized theory; these are applied
to the problem of a charged polymer confined to a spherical cavity in an
electrolyte solution. The results provide new insight into the physics of
confined polyelectrolytes.
