Journal article

Layering at liquid metal surfaces: Friedel oscillations and confinement effects

The structures of the liquid surface of sodium have been characterized with extensive first-principles molecular dynamics simulations based on ensemble density functional theory. Friedel oscillations in the electronic charge density at the free surface were found to persist across the solid-to-liquid melting transition, and remain decoupled from the atomic positions. Strong atomic layering was observed both at the liquid surface and at an artificial liquid solid interface, notwithstanding the absence of Friedel oscillations or under-coordinated atoms in the latter case. Confinement effects at these soft or hard boundaries drive the atoms into quasi-close-packed layers; even for this prototypical free electron metal Friedel oscillations are not relevant to ordering.


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