Theoretical Investigation of Differing Ion and Electron Temperatures in Hydrogen

Andrew Ng [1] has reported experimental results for silicon and gold in warm, dense matter conditions that have been modeled by use of distinct temperatures for the ions and electrons. Here we investigate the implications of such differing ion and electron temperatures for hydrogen using path-integral molecular dynamics (PIMD) for protons which interact with electrons descibed by orbital-free density functional theory (OF-DFT). Temperatures ranging from room temperature to many kilokelvin are considered for the protons, while the electron temperatures are fixed in the kilokelvin range. Recent advances [2] in OF-DFT not only allow for faster generation of first principles forces but also include the effects of temperature on the electron density. Comparisons are made with classical molecular dynamics to allow us to quantify the quantum nuclear effects captured by PIMD.\\[4pt] [1] A. Ng, Int. J. Quantum Chem., 112, 150 (2012).\\[0pt] [2] V. V. Karasiev, D. Chakraborty, O. A. Shukruto, and S. B. Trickey, Phys. Rev. B 88, 161108(R) (2013).