Fig. 14. Negligible effects of anharmonicity in v-SiO₂ described with the BKS potential.

Evaluating the conductivity using the protocol to determine the bulk limit yields an anharmonic rWTE conductivity (solid purple) that differs only about 4% from the bulk limit of the AF conductivity (dotted purple, evaluated using a Gaussian broadening ℏη = 4 cm⁻¹ determined from a convergence test analogous to that reported in Fig. 2). In contrast, evaluating the AF and WTE conductivities at q = 0 only (and using a Lorentzian broadening ℏη = 1.6 cm⁻¹ in the former case) yield values that strongly underestimates the bulk value for the AF conductivity (dotted orange) and weakly underestimates the Wigner conductivity (solid orange), respectively.