Prediction of the local structure of liquid and supercooled tantalum

We report first principles molecular dynamics simulations to predict the short-range order of liquid and supercooled tantalum. The results give support to characterize the transitory phase which occurs during solidification from highly undercooled tantalum liquid, as observed in ultravacuum drop tube experiments. The local short range order determined in the supercooled liquid displays a complex polytetrahedral type order, very close to that of the A15 phase. We have also determined the melting temperature of the A15 phase in fine agreement with the experimental melting temperature of the transitory phase, which represents a first step in the understanding of the solidification path.