Browsing by Author "Chen, Lin-Yuan"

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Analysis of local bond-orientational order for liquid gallium at ambient pressure: Two types of cluster structures
(2016-07-14)
Chen, Lin-Yuan
;
Tang, Ping-Han
;
Wu, Ten-Ming
;
物理研究所
;
Institute of Physics
In terms of the local bond-orientational order ( LBOO) parameters, a cluster approach to analyze local structures of simple liquids was developed. In this approach, a cluster is defined as a combination of neighboring seeds having at least n(b) local-orientational bonds and their nearest neighbors, and a cluster ensemble is a collection of clusters with a specified n(b) and number of seeds n(s). This cluster analysis was applied to investigate the microscopic structures of liquid Ga at ambient pressure ( AP). The liquid structures studied were generated through ab initio molecular dynamics simulations. By scrutinizing the static structure factors ( SSFs) of cluster ensembles with different combinations of n(b) and n(s), we found that liquid Ga at AP contained two types of cluster structures, one characterized by sixfold orientational symmetry and the other showing fourfold orientational symmetry. The SSFs of cluster structures with sixfold orientational symmetry were akin to the SSF of a hard-sphere fluid. On the contrary, the SSFs of cluster structures showing fourfold orientational symmetry behaved similarly as the anomalous SSF of liquid Ga at AP, which is well known for exhibiting a high-q shoulder. The local structures of a highly LBOO cluster whose SSF displayed a high-q shoulder were found to be more similar to the structure of beta-Ga than those of other solid phases of Ga. More generally, the cluster structures showing fourfold orientational symmetry have an inclination to resemble more to beta-Ga. Published by AIP Publishing.
Clusters of Local Bond-Orientational Order in Liquid Gallium: Studies of ab initio and Classical MD Simulations
(2018-01-01)
Chen, Lin-Yuan
;
Wu, Ten-Ming
;
物理研究所
;
Institute of Physics
The structure of liquid Ga at ambient pressure (AP) were generated separately via ab initio and classical molecular dynamics simulations, and analysed with a cluster approach developed in terms of the local bond-orientational order (LBOO) parameters. Two types of cluster structures were found in both simulated liquids, one typified by sixfold orientational symmetry and the other showing fourfold orientational symmetry: The static structure factors (SSF) of the former are akin to that of the hard-sphere (HS) fluid; however, the SSFs of the latter display either an asymmetric first peak with a shape different from that of the HS fluid or even a shoulder on the high-q side of the first peak, similar as the anomalous SSF of liquid Ga at AP.