Commun. Comput. Phys., 6 (2009), pp. 730-742. Effect of the Equilibrium Pair Separation on Cluster Structures Y. Yang 1, D. Y. Sun 1*1 State Key Laboratory of Precision Spectroscopy and Department of Physics, East China Normal University, Shanghai 200062, China. Received 26 July 2008; Accepted (in revised version) 16 January 2009 Available online 5 March 2009 Abstract The effect of the equilibrium pair separation on the evolution of cluster structures is investigated based on a new proposed pair potential. The computational results demonstrate that the potential with large equilibrium pair separation stabilizes decahedra and close-packed structures, while disordered structures appear for the potential with small equilibrium pair separation. The icosahedral clusters are dominated in the middle range of equilibrium pair separation. For the small size clusters ($N\leq24$) the dominated structural motif is the polytetrahedra, which is almost independent of the details of the potential. Notice: Undefined variable: ams in /var/www/html/issue/abstract/readabs.php on line 163 PACS: 61.46.Bc, 36.40.Mr Key words: Cluster structure, pair potential. *Corresponding author. Email: 52060602010@ecnu.cn (Y. Yang), dysun@phy.ecnu.edu.cn (D. Y. Sun)