Figure 1.

Comparison of potential energy fluctuations of atoms that are caged (atom 1) and atoms that are involved in collective string-like motion (atom 2) over the timescale longer than the lifetime of the strings t^* = 130 ps where N = 2899 at T = 1000 K. a) Potential fluctuations of individual atoms 1 and 2 within the interfacial region of NP. Note the correlation between potential energy changes and the spikes in the local Debye-Waller factor, <u²> for atom 2. b), c) Potential energy and particle displacements Δr of type 2 atoms at T = 1400 K where the y-axis denotes time in units of the caging time at which <u²> is defined. The time on the y-axis extends to the string lifetime, t*. d), e) E(t) and displacement plots for an array of normal (type 1) atoms along a crystal face having the same length of the string in b), c).