Beecroft Building, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU
Dr Chandre Dharma-wardana, National Research Council of Canada
Abstract
We begin by discussing what we mean by warm dense matter (WDM). In WDM systems, the
density and the temperature are such that there are always some free electrons characterized by a
Fermi Energy EF . The temperature T, while being nominally very “hot”, is such that T/EF itself is
small, justifying the name “warm” dense matter [? ? ? ]. Such matter, found in planetary and steller
systems [? ] or under conditions of nuclear fusion, is now routinely produced in the laboratory using
high-energy lasers, and studied using modern pump-probe diagnostics, x-ray diffraction, Thomson
Scattering etc., using multi-messenger approaches [? ]. WDM contains partially or fully ionized
atoms, boumd electons, partially bpund or free electrons, and they all interact via long-ranged
Coulomb interactions.
In the second half of the talk we discuss theoretical models of WDM, using quantum statistical
mechanics and many-body theory. The most important many-body theory today is density
functional theory (DFT). DFT replaces the electron-electron and ion-ion many-body problems by
effective one-body problems. We briefly discuss how DFT is used in DFT-MD and in the neutralpseudo-
atom (NPA) method [? ? ]. NPA is a computationally economical first-principles DFT
method. Some examples from recent work on Equations of State (EOS), plasma phase transitons,
conductivity calculations, and X-ray Thomson scattering (XRTS) will be presented.
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