The lifting of degeneracy resulting from the addition of SOC has a clear impact on hole transport. Indeed, for transport in semiconductors, only energies near the top of the VBM are relevant. As depicted in Figure , the function -𝑣 VB 𝜏 VB 𝜕𝑓 𝜕𝜀 𝛿(𝜀 -𝜀 VB ), which once integrated provides direct access to the RTA hole mobility, quickly approaches zero for energies further from the Fermi level. This means that only the electronic states covered by this function participate in the hole transport. As a result, the inclusion of SOC in CuI leads to the complete removal of a scattering channel, as the split-off band is no longer included in the energy windows responsible for transport, even at higher temperatures. Using ABINIT, we obtain a converged IBTE mobility of 162 cm 2 V -1 s -1 at 300 K with SOC and dynamical quadrupoles (Q * ) using 162 × 162 × 162 𝐤-and 𝐪-point grids (refer to Figure ). The inclusion of SOC leads to an enhancement in mobility by removing a scattering channel. Note that, despite the increase in mobility due to the effect of SOC on the electronic bands, its effect on phonons remains negligible on both phonon band structure and mobility, as shown in Figures and. The integration of Q * , the next order of correction to dynamical dipoles, in the computation is also necessary to obtain accurate results , preventing an error of about 15% in the case of CuI.