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The one-dimensional Lennard-Jones system: collective fluctuations and breakdown of hydrodynamics

Stefano Lepri·Paolo Sandri·Antonio Politi
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Abstract

The dynamical correlations of a model consisting of particles constrained on the line and interacting with a nearest--neighbour Lennard--Jones potential are computed by molecular--dynamics simulations. A drastic qualitative change of the spectral shape, from a phonon--like to a diffusive form, is observed upon reducing the particle density even ad moderate temperatures. The latter scenario is due to the spontaneus fragmentation of the crystal--like structure into an ensemble of "clusters" colliding among themselves. In both cases, the spectral linewidths do not follow the usual q^2 behaviour for small wavenumbers q, thus signalling a breakdown of linearized hydrodynamics. This anomaly is traced back by the presence of correlations due to the reduced dimensionality.

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Stefano Lepri, Paolo Sandri, Antonio Politi. 2005-09-01. The one-dimensional Lennard-Jones system: collective fluctuations and breakdown of hydrodynamics. https://doi.org/10.1140/epjb%2Fe2005-00360-7

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