Structural dynamics of clusters near melting

Unlike their bulk counterparts, clusters show a smooth transition from a low-temperature solidlike to a high-temperature liquidlike phase. Previous studies have established the variation of maximum Lyapunov exponent and the presence of 1/f noise in the power spectra of potential energy fluctuation as ‘‘dynamical indicators’’ of this transition. Here we propose that the coexistence can be efficiently studied using the self-part of the dynamic structure factor (DSF). To support our claim, we present molecular dynamics simulation results for the ${\mathrm{Ar}}_{13}$ cluster. We find that the spectral features of the DSF are strongly wavelength dependent and its long time behavior is anomalous, a result of the dynamic excursion between the two coexisting phases. © 1996 The American Physical Society.