A minimal description of morphological hierarchy in two-dimensional aggregates

A dimensionless parameter Λ is proposed to describe a hierarchy of morphologies in two-dimensional (2D) aggregates formed due to varying competition between short-range attraction and long-range repulsion. Structural transitions from finite non-compact to compact to percolated structures are observed in the configurations simulated by molecular dynamics at a constant temperature and density. Configurational randomness across the transition, measured by the two-body excess entropy S 2 , exhibits data collapse with the average potential energy &z.egrm; of the systems. Independent master curves are presented among S 2 , the reduced second virial coefficient B 2 * and Λ , justifying this minimal description. This work lays out a coherent basis for the study of 2D aggregate morphologies relevant to diverse nano- and bio-processes. A single dimensionless parameter is proposed to characterise the morphology of two-dimensional aggregates by their structural randomness.