We investigate the low temperature properties of two-dimensional
Lennard-Jones glass films, prepared in silico both by liquid cooling and by
physical vapor deposition. We identify deep in the solid phase a crossover
temperature T∗, at which slow dynamics and enhanced heterogeneity emerge.
Around T∗, localized defects become visible, leading to vibrational
anomalies as compared to standard solids. We find that on average, T∗
decreases in samples with lower inherent structure energy, suggesting that such
anomalies will be suppressed in ultra-stable glass films, prepared both by very
slow liquid cooling and vapor deposition.Comment: 10 pages including appendices, 8 figures. Version accepted for
Physical Review Material