Fig. 4: Subsequent pop-in behavior in molecular dynamics simulation at 5 K on the (100) BCC Fe surface.

Defect structure immediately (a) before and (b) after a subsequent pop-in (central symmetry parameter coloring43), von Mises stress distribution immediately (c) before and (d) after a subsequent pop-in, and (e) the corresponding load-displacement curve. f Spatial distribution of von Mises atomic-strain-invariant ηMises. Only atoms satisfying ηMises > 0.15 are displayed. g Spatial distribution of atomic displacement along loading direction ([100]), Δz, normalized by displacement burst Δh. Only atoms satisfying Δz/Δh > 0.25 are displayed. The von Mises stress distribution is shown on a (010) plane passing through the indenter central axis. The movies of the dislocation pattern and the stress-distribution evolution during the simulation can be found in Supplementary Movie 1. See also Supplementary Note 16 for (111) BCC Fe and (100) FCC Cu.