Lowest-energy structures of 13-atom binary clusters: Do icosahedral clusters exist in binary liquid alloys?

Although the existence of 13-atom icosahedral clusters in one-component close-packed undercooled liquids was predicted more than half a century ago by Frank, the existence of such icosahedral clusters is less clear in liquid alloys. We study the lowest-energy structures of 13-atom AxB13-x Lennard-Jones binary clusters using the modified space-fixed genetic algorithm and the artificial Lennard-Jones potential designed by Kob and Andersen. Curiously, the lowest-energy structures are non-icosahedral for almost all compositions. The role played by the icosahedral cluster in a binary glass is questionable.