Formal Poisson (co)homology of the Lefschetz singularity

We compute the formal Poisson cohomology groups of a real Poisson structure $\pi$ on ${\mathbb{C}}^2$ associated to the Lefschetz singularity $(z_1,z_2)\mapsto z_1^2+z_2^2$. In particular we correct an erroneous computation in the literature. The definition of $\pi$ depends on a choice of volume form. Using the main result we formally classify all Poisson structure arising from different choices of volume forms.