Correlation between local viscosity and the atomic-level stresses in liquids.

Liquids are ubiquitous, but the atomic origin of the viscosity remains unknown because of structural disorder. To study the relationship between viscosity and local structures we performed molecular dynamics simulations on various metallic liquids. Here the local structures of the liquids are characterized by the atomic-level stresses which describe the local mechanical states. We showed strong correlation between local viscosity and atomic-level stress in the liquids; for example, the atomic sites under compression are more unstable against shear than those under tension. The results indicate a universal structure-dynamics relationship in liquids.