Turning now to the different approximations used for the polarizability tensor α, we find that α DFPT and α µ Berry ind yield almost identical MD-based spectra. The good agreement is not surprising since α µ Berry ind can be viewed as the non-analytic variant of α DFPT . The derivative ∂µ α /∂E β (Equation ( )) is computed analytically in DFPT and numerically in the induced dipole approach. In both cases, µ α corresponds to a Berry phase dipole moment. The comparison of the α µ Berry ind and α µ MLWF ind reveals that, in line with the observations for IR, we obtain identical spectra from the Berry phase and MLWF-based approaches.