\(\phi_{\text{AB}}\left(\mathbf{r}\right)=\sum_{I}{\phi^{I}(\mathbf{r})}+\sum_{I<J}{{\phi}^{\text{IJ}}(\mathbf{r})}+\sum_{\alpha}\frac{Z_{\alpha}}{|\mathbf{r}-\mathbf{R}_{\alpha}|},\) (5)