### Warm Dense Matter

(Figure by Mike Desjarlais)

Warm dense matter (WDM) is encountered in systems as diverse as the interiors of giant planets and in the pathway to inertial confinement fusion. WDM is challenging to theory and simulation because it occurs inconveniently, for theory, between the comparatively well-studied plasma and condensed matter regimes. Both the Coulomb coupling parameter \(\Gamma := Q^2/(r_s k_B {\rm T}) \) and electron degeneracy parameter \(\Theta := k_B {\rm T}/\epsilon_F\) are approximately unity for WDM. (\(Q =\) relevant charge, \(r_s =\) Wigner radius, \(\epsilon_F =\) electron Fermi energy, \({\rm T} =\) temperature, \(k_B =\) Boltzmann constant.) A non-perturbative treatment therefore is required.

Contemporary computations on WDM
are dominated by use of the
Kohn-Sham realization of thermal density functional theory (DFT)
to generate a potential surface for
ionic motion (treated classically). The great majority of these
calculations use
approximate ground-state exchange-correlation functionals, \(E_{xc}\),
with the XC temperature-dependence picked up implicitly from the
\(\rm T\)-dependence of the density \(n({\mathbf r},{\rm T})\).
Though fruitful, this approach is not without potential difficulties.

→ OFDFT

#### Links of Interest

- HEDLP Report
Chapter 6 describes and motivates WDM research. (Image at left from this report.)

- IPAM Workshop IV (2012) Book
Chapter 3 is our work. Reprint at Publications.

- Los Alamos Nat. Lab. Dense Plasma Theory site
Includes links to their publications, a useful plasma parameter calculator, and informative videos.

- Redmer Group, TU Rostock
- LCLS site for Matter at Extreme Conditions