Dynamics of liquid and strongly supercooled alkali metals by instantaneous normal-mode analysis.

Abstract

The spectrum of instantaneous normal modes has been evaluated by molecular dynamics simulation for cesium in liquid and glassy states. The velocity autocorrelation function derived from the real-frequency part of the spectrum compares favorably with that calculated directly from simulation data, especially for the glassy state. We have pushed this comparison to the first memory-function level. It appears that the normal-mode analysis gives the correct short-time behavior, where correlated binary collisions play an important role. Such agreement extends toward intermediate times in the glassy state, where solidlike features are manifested by strong oscillations.