Freezing transitions in colloidal nanoparticles: Interplay of dispersive and electrostatic interactions in confined two-dimensional systems

We have used the classical density functional theory (DFT) of freezing to study the phase behavior of a two-dimensional system of colloidal nanoparticles interacting via a combination of hard-core electrostatic and Van der Walls forces. Pair-correlation functions, used as the lowest-order structural input in DFT, were calculated using Percus–Yevick integral equation theory. By tuning the relative strength of dispersion and electrostatic interactions through a mixing parameter, we systematically investigate the effects on the liquid–solid phase diagram . The results emphasize the importance of long-range dispersive forces that, in combination with electrostatic interactions, enable the formation of stable triangular solid phases.