The slope that best describes the experimental data (dashed line in Figure ), however, is 2 times larger than what is predicted from Eq. 5. This is not expected to be the result of a drastic misestimation of the 𝜔 ̅ 7 /𝜔 ̅ 6 ratio. It is more likely to be an artifact of assuming that all frequencies contribute equally to ionic transport (i.e. using the arithmetic average frequency 𝜔 ̅ in Eq. 3).