Pressure and Electrical Resistivity Measurements on Hot Expanded Metals: Comparisons with Quantum Molecular Dynamics Simulations and Average-Atom Approaches

We present experimental results on pressures and resistivities of expanded nickel and titanium at respective densities of 0.1 g/cm3 and 0.2 g/cm3, and in a range of temperature of 1-3 eV that corresponds to the warm dense matter (WDM) regime. These data are used to benchmark different theoretical approaches. A comparison is presented between fully 3-dimensional quantum molecular dynamics (QMD) methods, based on density functional theory, with average-atom (AA) methods, that are essentially one dimensional. AA methods are used to identify interband transitions and photoionization thresholds. In this regime the evaluation of the thermodynamic properties as well as electrical properties is difficult due to the concurrence of density and thermal effects which directly drive the metal-non-metal transition. QMD simulations are also helpful to give a precise estimation of the temperature of experiments which is not directly accessible [1] (c) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)