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arXiv · 1804.09104

Ion-ion dynamic structure factor, acoustic modes and equation of state of two-temperature warm dense aluminum

L. Harbour·G. D. Förster·M. W. C. Dharma-wardana·L. J. Lewis
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Abstract

The ion-ion dynamical structure factor and the equation of state of warm dense aluminum in a two-temperature quasi-equilibrium state, with the electron temperature higher than the ion temperature, are investigated using molecular-dynamics simulations based on ion-ion pair potentials constructed from a neutral pseudoatom model. Such pair potentials based on density functional theory are parameter-free and depend directly on the electron temperature and indirectly on the ion temperature, enabling efficient computation of two-temperature properties. Comparison with ab initio simulations and with other average-atom calculations for equilibrium aluminum shows good agreement, justifying a study of quasi-equilibrium situations. Analyzing the van Hove function, we find that ion-ion correlations vanish in a time significantly smaller than the electron-ion relaxation time so that dynamical properties have a physical meaning for the quasi-equilibrium state. A significant increase in the speed of sound is predicted from the modification of the dispersion relation of the ion acoustic mode as the electron temperature is increased. The two-temperature equation of state including the free energy, internal energy and pressure is also presented.

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L. Harbour, G. D. Förster, M. W. C. Dharma-wardana, L. J. Lewis. 2018-04-25. Ion-ion dynamic structure factor, acoustic modes and equation of state of two-temperature warm dense aluminum. https://doi.org/10.1103/physreve.97.043210

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