Volume heterogeneity in liquid Cu near the dynamical crossover temperature T-a

MH Sun and XW Yao, JOURNAL OF NON-CRYSTALLINE SOLIDS, 556, 120559 (2021).

DOI: 10.1016/j.jnoncrysol.2020.120559

We present the results of a molecular dynamics simulation in which we investigate whether a supercooled monometallic liquid exhibits structural heterogeneities. Using the vomnoi construction, we calculate the atomic excess volume v(a) and its distribution in liquid Cu in the 3D space. We find that v(a) is not distributed homogeneously in the liquid, atoms with smaller v(a) aggregate to form solid-like clusters which give rise to the dynamical heterogeneity. In the cooling process, these solid-like clusters increase rapidly from T-a showing the structural origin of dynamical crossover. we demonstrate that it is the excess volume of the cluster that governs the liquid dynamics below T-a. We also find that the atomistic motion is controlled by the excess volume of its neighbors demonstrating the enhancing collective motion feature below T-a.

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