Figure 5.

Example of coarse-graining. Instead of computing the interactions between all hydrogens and oxygens of water molecules, one can construct a higher level representation as shown by the yellow circles. For the coarse-grained representation to be a meaningful one, both systems must produce the same g(r) as described in the text. In the coarse-grained representation, the electrostatic interactions are included in the new effective coarse-grained potential (see text) that is obtained first by inverting Eq. (19) and then iterating it.^{161,553,565,566}