the present study, are compared to those obtained using more common molecular calculations of AIM properties. For the set of $168$ neutral molecules previously studied by Bultinck *et al.*,[@BultinckP:2007JCP_HirRef; @VanDamme_Bultinck:JCTC2009] geometry optimization and Hirshfeld-I charge calculations are performed at the Local Spin Density Approximation[@HohenbergKohn:PR1964; @KohnSham:PR1965] level with the Slater exchange functional[@SlaterJC:1974] and the VWN$5$ correlation functional[@VoskoWilkNusai:CanJP1980] as implemented in Gaussian-03.[@Gaussian03] Numerical integrations are carried out using Becke’s integration grid with $170$ angular points in the Lebedev-Laikov grid.[@BeckeAD:1987JCP; @LebedevVI_grid:1999DokladyMath] The Hirshfeld-I charges are considered converged if the largest change in charge of any atom is below $0.0005$e.

Hirshfeld methods
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The basic idea behind the Hirshfeld method,[@HirshfeldFL:1977TCA] also known as the stockholder method, is that the AIM share the charge density in each point of space. This means that the AIM CDD becomes a weighted partition of the molecular CDD. Formally this can be written as: $$\begin{aligned}
\rho_{mol}(\mathbf{r})&=&\sum_{A}{\rho_A^{AIM}(\mathbf{r})}\nonumber\\
\rho_A^{AIM}(\mathbf{r})&=&w_{A}^{H}(\mathbf{r})\rho_{mol}(\mathbf{r}) \qquad \forall \mathbf{r}\\
\mathrm{with\ }\sum_{A}{w_{A}^{H}(\mathbf{r})} &\equiv& 1 \nonumber,\end{aligned}$$ with $\rho_{mol}(\mathbf{r})$ and $\rho_{A}^{AIM}(\mathbf{r})$ the CDDs for the molecule and the AIM. All sums are taken over the entire set of AIM, and  is the Hirshfeld weight function for atom $A$. From these equations the Hirshfeld weight can be written as: $$w_{A}^{H}(\mathbf{r})=\frac{\rho^{AIM}_{A}(\mathbf{r})}{\sum_{B}{\rho_{B}^{AIM}(\mathbf{r})}}.\label{eq:Hir_w_mol}$$ Since the 