(173e) Structural and Dynamical Properties of Atomic Thin Films

Recent discovery of stable glasses by Ediger and coworkers [1] has spurred an increased interest in understanding the structural and dynamical properties of thin films. Here, we use molecular dynamics (MD) simulation to study thin films of the Kob-Anderson binary Lennard Jones system [2], and compute their structural and dynamical properties as a function of distance from the wall. The computed structural properties include profiles of densities, internal energies, normal and lateral stresses and lateral radial distribution functions, while the dynamical properties calculated on a layer-by-layer basis are the structural relaxation times and lateral diffusivities. A monotonic increase of relaxation times is observed along the free interface, which is consistent with earlier observations on free-standing films [3]. The dynamical heterogeneity in the vicinity of the wall is however more subtle and depends both on the strength of wall-liquid interactions and the local structure of the film in the vicinity of the wall. In addition, the film is strongly stratified in the liquid-wall interface, but this stratification is not usually accompanied with long-range lateral order, and the extent of such long-range order also depends on the strength of wall-liquid interaction. 

1- Swallen SF, Kearns KL, Mapes MK, Kim YS, McMahon RJ, Ediger MJ, Wu T, Yu L, Satija S, Science 315(5810): 353-6 (2007).

2- Kob W, Andersen HC, Phys. Rev. E 51: 4626-41 (1995).

3- Shi Z, Debenedetti PG, Stillinger FH, J. Chem. Phys. 134: 114524 (2011).