5 FIG. 3: Time dependence of the mean squared displacement curves for both the oxygen and germanium ions. The tem- peratures ranges between 3600 K and 5000 K. FIG. 4: Diffusion coefficients obtained with a DIPPIM po- tential at different temperatures; data points obtained with both the original and rescaled OE potentials at 3600 K are also presented. FIG. 2: Radial distribution functions obtained from the 300 K simulations with the DIPPIM and original OE interac- tion potentials. These are compared to the experimental ones obtained from neutron diffraction experiments $^{5}$. conclude that our DIPPIM potential gives a good agree- ment with the experimental data as well. A direct com- parison with experimental data might be done by using the only published datum ( D$_{O}$ = 7 × 10 − 10 cm $^{2}$s − $^{1}$) on the oxygen diffusion constant $^{25}$, at T =1440 K. However, such a low diffusion coefficient would involve an impossi- bly long simulation run. It is also interesting to see that the rescaled OE poten- tial yields too fluid a melt if compared with the original OE and DIPPIM potentials and with experimental data.