In the two-dimensional(2D)melting transition of colloidal systems,the hexatic-isotropic(H-I)transition can be either first-order or continuous.However,how particle dynamics differs at the single-particle level during ...In the two-dimensional(2D)melting transition of colloidal systems,the hexatic-isotropic(H-I)transition can be either first-order or continuous.However,how particle dynamics differs at the single-particle level during these two different melting transitions remains to be disclosed.In this work,by Brownian dynamics(BD)simulations,we have systematically studied the dynamic behavior of corner-rounded hexagons during the H-I transition,for a range of corner-roundness𝜁=0.40 to 0.99 that covers the crossover from the continuous to first-order nature of H-I transition.The results show that hexagons with𝜁≤0.5 display a continuous H-I transition,whereas those with𝜁≥0.6 demonstrate a first-order H-I transition.Dynamic analysis shows different evolution pathways of the dominant cluster formed by migrating particles,which results in a droplet-like cluster structure for𝜁=0.40 hexagons and a tree-like cluster structure for𝜁=0.99 hexagons.Further investigations on the hopping activities of particles suggest a cooperative origin of migrating clusters.Our work provides a new aspect to understand the dependence of the nature of H-I transition on the roundness of hexagons through particle dynamic behavior.展开更多
基金supported by the National Natural Science Foundation of China(11874277,21621004 and 12104453)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB33030300).
文摘In the two-dimensional(2D)melting transition of colloidal systems,the hexatic-isotropic(H-I)transition can be either first-order or continuous.However,how particle dynamics differs at the single-particle level during these two different melting transitions remains to be disclosed.In this work,by Brownian dynamics(BD)simulations,we have systematically studied the dynamic behavior of corner-rounded hexagons during the H-I transition,for a range of corner-roundness𝜁=0.40 to 0.99 that covers the crossover from the continuous to first-order nature of H-I transition.The results show that hexagons with𝜁≤0.5 display a continuous H-I transition,whereas those with𝜁≥0.6 demonstrate a first-order H-I transition.Dynamic analysis shows different evolution pathways of the dominant cluster formed by migrating particles,which results in a droplet-like cluster structure for𝜁=0.40 hexagons and a tree-like cluster structure for𝜁=0.99 hexagons.Further investigations on the hopping activities of particles suggest a cooperative origin of migrating clusters.Our work provides a new aspect to understand the dependence of the nature of H-I transition on the roundness of hexagons through particle dynamic behavior.
