  The Coulomb log (log {\Lambda}) approximation is widely used to approximate
electron transport coefficients in dense plasmas. It is a classical
approximation to the momentum transport cross section. The accuracy of this
approximation for electrical conductivity in dense plasmas is assessed by
comparing to fully quantum mechanical calculations for realistic scattering
potentials. It is found that the classical approximation is accurate to +/-10%
when log {\Lambda} > 3, irrespective of the plasma species. The thermodynamic
regime (density and temperature) for which log {\Lambda} > 3 corresponds to
does, however, strongly depend on the material. For increasing Z, log {\Lambda}
is greater than 3 for increasingly high temperatures and lower densities.
