Dirac variables and zero modes of Gauss constraint in finite-volume two-dimensional QED

The finite-volume QED(1+1) is formulated in terms of Dirac variables by an explicit solution of the Gauss constraint with possible nontrivial boundary -conditions taken into account. The intrinsic nontrivial topology of the ga uge group is thus revealed together with its zero-mode residual dynamics. T opologically nontrivial gauge transformations generate collective excitatio ns of the gauge field above Coleman's:ground state, that are completely dec oupled from local dynamics, the latter being equivalent to a free massive s calar field theory.