1. Sample the N e (r, u) integral (Eq. 1) for a predefined range of the interelectronic distances u. Note that N e monotonically increases with u and approaches N (number of electrons) at large u. We use 1000 u grid points. The interval [u min , u max ] is adjusted at each r such that N e (r, u max ) ≤ N -0.0001. In this way, we cover only the necessary u region and increase the overall accuracy of the approach. 2. Calculate the initial radii, a i (r), implicitly defined as: N e r, a i (r) = N -1 (Eq. 13).