  In this paper we study a special class of Calabi-Yau algebras (in the sense
of Ginzburg): those arising as the fundamental group algebras of acyclic
manifolds. Motivated partly by the usefulness of `superpotential descriptions'
in motivic Donaldson-Thomas theory, we investigate the question of whether
these algebras admit superpotential presentations. We establish that the
fundamental group algebras of a wide class of acyclic manifolds, including all
hyperbolic manifolds, do not admit such descriptions, disproving Ginzburg's
conjecture regarding them. We also describe a class of manifolds that do admit
such descriptions, and discuss a little their motivic Donaldson-Thomas theory.
Finally, some links with topological field theory are described.
