Fluctuation between icosahedral and body-centered-cube short-range orders in undercooled Zr liquid

Ab initio molecular dynamics simulations are performed to study the liquid and undercooled liquid of zirconium. Local structure orders in the liquid at temperatures from 2500 K down to 1830 K are analyzed by using the recently developed cluster alignment method. Our study clearly shows the presence of body-centered-cube (BCC) short-range order in the undercooled liquid in addition to icosahedral order. A strong fluctuation and competition between the short-range icosahedra and BCC orders in the undercooled liquid at 1830 K are also demonstrated from the cluster alignment scheme. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3662189]