Fig. 4.

Decomposition of the SPW92 second-order spin-polarization potential $w_{\text{ref}}^{(2)}(\mathbf{r})$ for the HCO molecule. The panels depict: (a) the potential, without approximation; (b) the one- and two-body partitioned cluster approximation [Eq. (53)]; and (c) the one-body partitioned cluster approximation; i.e., W_ab = 0 for all pairs. The colors represent the value of these potentials in the plane formed by the atoms. The x- and y-axis are in units of Bohr and the color scale is E_h. The solid lines are isocontour values of −0.7, −1.5, −3, and −6 E_h