**3.3 The polarisation**

The polarisation along the c-axis was calculated for a range of electric fields and temperatures. Figure 7 shows the polarisation as a function of time. Over the initial 5000

Fig. 7. The polarisation in c-axis with an applied field of 743MV/m as a function of time.

Fig. 6. Position of the first six sodium ions in c-axis when electric field of 743MV/m was

The polarisation along the c-axis was calculated for a range of electric fields and temperatures. Figure 7 shows the polarisation as a function of time. Over the initial 5000

Fig. 7. The polarisation in c-axis with an applied field of 743MV/m as a function of time.

applied along the c-axis to the hollandite model at 5001th time interval.

**3.3 The polarisation** 

intervals, the polarisation tends to fluctuate around zero. Once the electric field is applied at 5001th interval, the polarisation increases rapidly to around 0.7 C/m2 and after that sudden increase, the polarisation remains at an average of that value for the rest of the time intervals. The results under different electric field are similar, but a smaller field gives a smaller polarisation. A running average of the polarisation was taken over 100 intervals and only the results starting from 5001th intervals are taken into account. This is because the results of interest are those under the effect of electric field.

Figure 8 gives the continuous average for the polarisation as a function of time. The plot obtained was not as noisy as the polarisation plot shown in figure 7, as the running average over 100 intervals eliminates vibration periods at 10-13 s and shorter.

Fig. 8. Continuous average for the polarisation with an applied field of 743MV/m as a function of time.
