Dynamics and spatial correlation of voids in dense two dimensional colloids

作者：Kim Jeongmin^*; Sung Bong June

来源：Journal of Chemical Physics, 2014, 141(1): 014502.

DOI：10.1063/1.4885035

Two dimensional (2D) colloids show interesting phase and dynamic behaviors. In 2D, there is another intermediate phase, called hexatic, between isotropic liquid and solid phases. 2D colloids also show strongly correlated dynamic behaviors in hexatic and solid phases. We perform molecular dynamics simulations for 2D colloids and illustrate how the local structure and dynamics of colloids near phase transitions are reflected in the spatial correlations and dynamics of voids. Colloids are modeled as hard discs and a void is defined as a tangent circle (a pore) to three nearest hard discs. The variation in pore diameters represents the degree of disorder in voids and decreases sharply with the area fraction (phi) of colloids after a hexagonal structural motif of colloids becomes significant and the freezing transition begins at phi approximate to 0.7. The growth of ordered domains of colloids near the phase transition is captured in the spatial correlation functions of pores. We also investigate the topological hopping probability and the topological lifetime of colloids in different topological states, and find that the stability of different topological states should be related to the size variation of local pores: colloids in six-fold states are surrounded by the most ordered and smallest pores with the longest topological lifetime. The topological lifetime of six-fold states increases by about 50 times as phi increases from liquid to hexatic to solid phases. We also compare four characteristic times in order to understand the slow and unique d

• 出版日期2014-7-7