The global relativistic energy loss cross section at high energies (neglecting radiation energy- losses and collective screening) is proportional to

c1 = (ln(2 (g vp)^2 / I_Bethe) - b^2) / vp^2

with b = vp / c and g = 1 / (1 - b^2)^0.5.

The corresponding non-relativistic expression is

c2 = ln(2 vp^2 / I_Bethe) / vp^2.

When selecting this option in elder CasP versions, all energy-loss values were simply scaled by a constant factor c1/c2.

The CasP versions beyond version 3.1 include an impact-parameter dependent realization of this effect (still neglecting radiation energy-losses and collective screening). Here we have adopted the simplified treatment using the g-correction factors exactly as shown in chapter 13 by J.D.Jackson in his book on ‘Classical electrodynamics’ (de Gruyter, 1981). However, the finite nuclear-size effect is currently not considered as a lower impact-parameter cut-off.