To shed light on the thermodynamic stability of the intermediate Na2V2(PO4)3 phase, detected with our SXRPD diffraction, we performed dedicated DFT calculations. Figure shows the thermodynamic properties of NaxV2(PO4)3 in the region of x = 1 -3 at 0 K, as computed by DFT. Figure shows the DFT mixing enthalpies (𝐻 *+"+,-in eq. 2) for all Na/vacancy orderings of the NaxV2(PO4)3 compositions. Using a convex hull minimization algorithm, all the ground-state configurations were obtained. It can be concluded that besides the endmembers Na1V2(PO4)3 and Na3V2(PO4)3, which are assigned to rhombohedral and monoclinic symmetry, respectively, a new phase Na2V2(PO4)3 appears as a stable configuration. However, Na2V2(PO4)3 shows a relatively low mixing enthalpy (ca. -23 meV/f.u.) with respect to Na1V2(PO4)3 and Na3V2(PO4)3, and this suggests that the intermediate phase may be metastable at room temperature. chemically as a pure phase will further clarify the discrepancies between the DFT data and our experimental models.