Velocity autocorrelation function in supercooled liquids: Long-time tails and anomalous shear-wave propagation

HL Peng and HR Schober and T Voigtmann, PHYSICAL REVIEW E, 94, 060601 (2016).

DOI: 10.1103/PhysRevE.94.060601

Molecular dynamic simulations are performed to reveal the long-time behavior of the velocity autocorrelation function (VAF) by utilizing the finite-size effect in a Lennard-Jones binary mixture. Whereas in normal liquids the classical positive t(-3/2) long-time tail is observed, we find in supercooled liquids a negative tail. It is strongly influenced by the transfer of the transverse current wave across the period boundary. The t(-5/2) decay of the negative long-time tail is confirmed in the spectrum of VAF. Modeling the long-time transverse current within a generalized Maxwell model, we reproduce the negative long-time tail of the VAF, but with a slower algebraic t(-3/2) decay.

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