Let $L$ be a cyclic differential graded Lie algebra. By transfer
theorem the cohomology $H(L)$ of $L$ has a cyclic $L_\infty$-algebra
structure. We prove that there is a potential function $W: H^1(L)-->\C$
such that the moduli space associated to the deformation of $L$ is the
critical locus of the differential $dW$. The Milnor number of the
holomorphic function $W$ is defined to be the Milnor number of $L$.

As an application, the Donaldson-Thomas differential graded Lie algebra
is a cyclic differential graded Lie algebra of dimension 3. We prove
that the associated $L_\infty$-algebra on the cohomology is still a
differential graded Lie algebra. The pointed Donaldson-Thomas invariant
is the Milnor number of this cyclic differential graded Lie algebra.