First-principles Study of Pb(111) Nanofilms in the Quantum Regime*

We report first-principles calculations to investigate surface free energy, interlayer spacing, surface stress, and surface self-diffusion barrier for Pb(111) films in the thickness range of 1 to 31 monolayers, where the quantum size effect (QSE) dominates. We show that similar to surface free energy, all these properties exhibit an oscillation behavior and a beating pattern as a function of film thickness. We will discuss correlations between these properties in terms of QSE.