Figure 3.

(a–c) ΔG_25 Å (=G_25 Å − G_40 Å) as functions of 1:1 salt concentration for the four-body systems which are calculated respectively by the pair-wise potential of mean force abstracted from two-body, three-body and four-body systems (denoted respectively by two nanoparticles ×6, three nanoparticles ×2, and four nanoparticles). (a) Z = −16e, (b) Z = −20e and (c) Z = −24e per nanoparticles. The insets show the PMF differences ΔΔG_25 Å defined by ΔG_25 Å(four) − ΔG_25 Å(two) × 6 (red; denoted by 4 − 2) and ΔG_25 Å(three) × 2 − ΔG_25 Å(two) × 6 (green; denoted by 3 − 2). (d–f) Net charge fraction within 8 Å from the surface of nanoparticles with x = 25 Å for Z = −16e (d), Z = −20e (e) and Z = −24e (f). The insets show the difference in number of binding ions within 8 Å from the surface of nanoparticles between four- and two-body systems (red; denoted by 4 − 2) as well as that between three- and two-body systems (green; denoted by 3 − 2).