‘On the a.c. electrical conductivity of a Lorentz gas’ by J. H. M. Fu and R. S. B.Ong, J. Plasma Phys. 2, 1968, P. 1.

Calculation of the electrical conductivity

The current density is expressed by

Using the dimensionless velocity c = (m/2θ;)½v and noting that the current density associated with the equilibrium distribution function f0 vanishes, we can write

g(k, c, w) is given formally by

where gns(k, c, w) is given by (2.15) in the original paper, and

with λ = (2θ/m)½/(w/k and δ the Dirac delta function.