Long time behaviour of the velocity autocorrelation function at low density and near critical point of simple fluids

R.F.A. Dib (1) , Fouzia Ould-Kaddour (1) , Dominique Levesque (2)

1 Laboratoire de Physique Théorique
2 LPT - Laboratoire de Physique Théorique d'Orsay [Orsay]

Numerous theoretical and numerical works have been devoted to the study of the algebraic decrease at large times of the velocity autocorrelation function of simple fluid particles. The derivation of this behaviour, so-called the long-time tail, generally based on linearized hydrodynamic makes no reference to any specific characteristic of the particle interactions. However, in the literature, doubts have been expressed on the possibility that by numerical simulations the long-time tail can be observed in all the fluid phase domain of systems where the particles interact by soft-core and attractive pair potentials. In this work, extensive and accurate molecular dynamics simulations establish that the predicted long-time tail of the velocity autocorrelation function exists in low density fluid of particles interacting by a soft-repulsive potential and near the liquid-gas critical point of a Lennard-Jones system. These results contribute to confirm that the algebraic decay of the velocity autocorrelation function is universal in the fluid systems.

Mots clés: long-time tail; low-density

Domaines: Physique Numérique [physics.comp-ph]

R.F.A. Dib, Fouzia Ould-Kaddour, Dominique Levesque. Long time behaviour of the velocity autocorrelation function at low density and near critical point of simple fluids. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, 2006, 74, pp.011202. ⟨hal-00278683⟩