  The controversy with respect to the role of electron-electron collisions in
the dynamic conductivity of dense plasmas is resolved. In particular, the dc
conductivity is analyzed in the low-density, non-degenerate limit where the
Spitzer theory is valid and electron-electron collisions lead to the well-known
reduction of the result for a Lorentz plasma. With increasing degeneracy, the
contribution of electron-electron collisions to the dc conductivity is
decreasing and can be neglected for the liquid metal domain where the
Ziman-Faber theory is applicable. We show how electron-electron collisions have
to be implemented in calculations based on the Kubo-Greenwood formula which is
prevalently applied in simulations for the frequency-dependent conductivity in
the warm dense matter region, i.e. for arbitrary degeneracy.

Plasma Physics