Stability and Phase Behaviour of Two-Dimensional Arrays

The van der Waals interaction due to the polarization of the metal cores constitutes the attractive term and the steric interaction between the thiol molecules on the two surfaces forms the repulsive term, where t is the interpartide distance. The Hamaker constant, A, for Pd nanocrystals, in toluene for instance, has been estimated to be 1.95 eV [140]. The calculated diameter of the area occupied by the thiol molecule (sa) on the particle surface is 4.3A [112]. The total energy is attractive 

The bright area in the middle encompasses systems that form close-packed organizations of nanocrystals. The surrounding darker area includes disordered or low-order arrangements of nanocrystals. The area enclosed by the dashed line is derived from calculations from the soft sphere model (reproduced with permission from [114]). 

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