| dc.description.abstract | For liquids confined by flat boundaries, microscopic structures and particle motions are determined by three important factors: thermal agitation, mutual interaction, and topological constraint of the flat boundary. Due to the interplay of mutual interaction and the topological constraint from the flat boundary, the particles nearby the boundary are lined up and their transverse motions are suppressed, leading to the formation of stacked layered structures nearby the boundary. Conversely, thermal agitation serves as the disordered source deteriorating layering. As the distance to the boundary decreases, the confinement effect intensifies, leading to a transition in micro-structures from a liquid state to layered arrangements. Despite its importance, understanding this layering transition down to the microscopic level is still an unexplored issue.
Recent studies in various nonlinear extend systems, such as forest fire, power grid failure, epidemic spread, colloids gelation, solid exhibiting yielding, and turbulent transitions in hydrodynamic flow and nonlinear waves, have demonstrated the order-disorder/disorder-order transitions under varying control parameters belong to the general category of percolating transition, the formation of a spanning network through the connection of active (inactive) sites, associated with the rapid smooth rise of the fraction of active (inactive) sites. With increasing (decreasing) drives, those systems exhibit smooth rapid increases in the fraction of disordered (ordered) sites, associated with the heterogeneous emergence of ordered (disordered) sites in the form of clusters, which can grow and form a percolating cluster spanning over the system. However, the generic behaviors of layering transition in cold liquids under confinement down to the microscopic level, and whether the generic transition behaviors also follow those governed by percolation theory remain unexplored.
Here, the above unexplored issues are investigated in a 3D Yukawa liquid confined by two parallel flat boundaries, using molecular dynamic simulation. The layered order sites (LOSs) and intralayer structural order sites (SOSs) in each layer are identified by calculating local layering and intralayer structural orders. Their correlation and the role of temperature on the layering transition are also studied.
It is found that, LOSs and SOSs exhibit strong positive spatial correlation. At a fixed low temperature, the fraction of LOSs (SOSs) shows a smooth rapid growth with decreasing distance to the boundary. LOSs (SOSs) emerge in the form of clusters with various sizes exhibiting power-law cluster size distributions. The scaling exponents of the power-law distribution gradually increase before a large percolating cluster spanning over the space appears, akin to the transition governed by percolation theory. | en_US |