As a consequence, no peak at the contact distance is noticed in the g(r) curves for this system, and even the approximation up to the distance of ca 6.5 nm where only one solvation layer separates the NPs is a slow process, as can be seen by the peak at 6.0 nm being smaller than those at ca. 9.0 nm along the whole simulation of this system while for the hydrophilic NPs in the same solvent this trend was inverted already at 100 ns. This shows that not only the 65 kJ/mol major barrier in this system provides a strong kinetic stabilization but also the secondary barrier slows down significantly the NPs approximation. In fact, the secondary barrier for the hydrophobic NPs in C8 solvent is as high as the only barrier for the aggregation of the same NPs in C4 (Figure ). Despite the positions of maxima and minima of the NP-NP radial distribution functions for the dispersions in C8 agree well with the positions of the extreme points in the pmf, one can question how much the pmf computed for a dimer of NPs can predict the distribution in a concentrated dispersion and vice versa. To tackle the question, the pmf was computed from the radial distribution functions between NPs in the dispersions in C8 IL at the last time interval (2000 to 2500 ns, black curves in Figure ) using Equation , where T is the temperature and R the ideal gas constant. The second term in Equation stands for the entropy variation associated with the change in the available volume when moving from a spherical shell of radius r 0 to a spherical shell of radius r (Equation ), a contribution that needs to be included in the pmf computed from the radial distribution function. Due to the poor sampling at the contact region in the dispersion of the hydrophilic particle and its total absence in the case of hydrophobic particles, only the region after the first maximum of the pmf was considered and the results are shown in Figure , with all the curves shifted to give the value of zero at 12.30, the same reference used for the pmfs in Figure . The pmf computed from the NP-NP distribution in the dispersion (black curve in Figure ) matches very well the long-range behavior of the dimer pmf,