  Dynamic heterogeneity as one of the most important properties in supercooled
liquids has been found for several decades. However, its structural origin
remains open for many systems. Here, we propose a new structural parameter to
characterize local atomic packing in metallic liquids. It is found that the new
parameter in a simulated metallic glass-forming liquid is closely correlated
with potential energy and atomic mobility. It also exhibits significant spatial
heterogeneities and these structural fluctuations show close correlation with
the spatial distribution of the long-time dynamic propensities. Therefore, our
results provide a direct evidence of the correlation between atomic structure
and dynamical heterogeneity.
