Local order and diffusive motions in simple liquids

In order to study the properties of the short-range order in simple liquids, a ‘‘moving average filter’’ is applied to the positions and velocities obtained from molecular dynamics simulations of L-J systems, in order to reduce the thermal motions. The fictitious systems that are obtained allow a be...

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Veröffentlicht in:The Journal of chemical physics 1995-02, Vol.102 (7), p.2864-2870
Hauptverfasser: González, Hernán J., Cernuschi-Frías, Bruno, Barraza, Néstor R., Cernuschi, Félix
Format: Artikel
Sprache:eng
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Zusammenfassung:In order to study the properties of the short-range order in simple liquids, a ‘‘moving average filter’’ is applied to the positions and velocities obtained from molecular dynamics simulations of L-J systems, in order to reduce the thermal motions. The fictitious systems that are obtained allow a better analysis, not only of the underlying structure, but also of the time-dependent low-frequency properties, such as diffusive motions. From the analysis of the correlation radial function g(r) and the recently proposed [S. Mazur, J. Chem. Phys. 97, 9276 (1992)] ‘‘neighborship distributions,’’ P(n,r), it is shown that the face-centered-cubic lattice is inadequate to model the local order in the liquid state. To study the nature of the diffusive motions, a spatial-dependent velocity correlation function is computed. It shows significant positive values for the filtered systems. This suggests a cooperative mechanism for diffusion. However, it seems that the collective motions do not involve large clusters, but rather small clusters and linear ‘‘chains’’ of molecules.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.468664