Topological features of atomic packings and the relation to glass-forming ability in metallic glass-forming systems

Molecular dynamics simulations were performed to study some model metallic glass-forming systems with distinct glass-forming ability (GFA), including monatomic metals and multicomponent alloys for understanding the physical origin of the GFA. Here the topological features of atomic packings in these systems were explored by employing the persistent homology (PH), a novel approach of computational algebraic topology to characterize the homology classes/Betti number and connection propensity of the densest packings. We found that the homology classes in all systems decrease with decreasing temperature, suggesting that the atomic packings generally become more and more heterogeneous during glass formation, but with different degrees. Moreover, we found that the connection propensity of the densest packings exhibits distinct evolution tendency in both multicomponent alloys and monatomic metals during cooling, and is consistent with the order of their GFA. This indicates that the connection propensity of the densest packings may be a general factor controlling the GFA of metallic glass-forming systems. Our findings demonstrate that the topological features of dense atomic packings in metallic glass-forming systems may be intrinsic in disordered structures and provide new insights into the structure-property relationship in glass-forming systems.