One can easily see from the exchange and correlation functionals above that the heuristic philosophy driving this model is the introduction of fictitious electron clouds by means of consecutive applications of the Laplace operator on the noninteracting atomic density contributions, thus, making each of these contributions spherically symmetric by construction. This is likely a limiting factor in our model, since capturing asymmetries in the interacting densities is likely to be more successfully achieved by the inclusion of atom-centered contributions that have no spherical symmetry in the fictitious interacting densities. An example where this plays a significant role is a water molecule with its lone electron pair which can clearly not be described by spherical densities residing on the oxygen atom. This may also have contributed to the requirement of having to use rather high order expansions (six or higher) to accurately model water dimer interactions in our previous model.