because the dimension of the associated Hilbert space increases exponentially with system size. To obtain results for correlated electron systems one therefore resorts to approximate techniques, which try to capture the relevant parts of the physics in the system. This paper deals with variational density matrix optimization (v2DM), a many-body method which removes the wave function from quantum mechanics by replacing it wth the two-body reduced density matrix (2DM), at the benefit of having nicer scaling properties. This appealing idea originates from the 1940’s with Husimi [@husimi] and was brought to focus by Coleman in his excellent review paper [@coleman]. In subsequent years a lot of effort was put in the formulation of the problem [@garrod; @kummer] and the first numerical calculations were performed [@fusco; @garrod_mih_ros]. However, some disappointing results [@mihailovic; @rosina] and the computational complexity of the problem caused activity in the field to drop. It wasn’t until Nakata [*et al.*]{} [@nakata_first] and Mazziotti [@mazziotti] introduced a numerical technique called semidefinite programming to v2DM, that interest in the field was renewed. Since then a lot of progress has been made, both by developing better algorithms suited to the physics problem at hand [@primal_dual; @maz_bp; @maz_prl; @nakata_last], as well as 