Effect of the liquid-like ionic structure on the electron-ion energy relaxation timescales in dense plasmas

In a recent publication [J. Daligault, D. Mozyrsky, Phys. Rev. E 75 (2007) 026402], we derived a general expression for the electron-ion energy relaxation rate in plasmas which, as a result of the small electron-ion mass ratio, expresses the relaxation rate in terms of the low-frequency electronic density fluctuations. Here we propose a practical model for the electronic density fluctuations in dense plasmas and apply this model to the calculation of the electron-ion energy relaxation rate. We find that the rate is only scarcely affected by the underlying liquid-like ionic disorder typical of dense matter. Relaxation rates obtained are systematically slightly larger than those predicted by the Fermi Golden Rule formula, in contradiction with the coupled-modes' theory that predicts values an order of magnitude lower. We also find that the discontinuity of the rate at melting is tiny, in contrast with the sharp increase of the electrical conductivity.