Second roton feature in the strongly coupled electron liquid.

We present extensive ab initio path integral Monte Carlo (PIMC) results for the dynamic properties of the finite temperature uniform electron gas (UEG) over a broad range of densities, 2 ≤ rs ≤ 300. We demonstrate that the direct analysis of the imaginary-time density-density correlation function (ITCF) allows for a rigorous assessment of the density and temperature dependence of the previously reported roton-type feature [Dornheim et al., Phys.