Modeling of the hk XRD bands shown in Fig. 4(a) using the Bragg-rod method. (a) Best simulation obtained for δ-MnO2 at pH 10 (dBi10). Sensitivity of the calculation to Na and nonbonded water molecules (b), to size distribution and strain (c), to strain (d), and to size distribution (e). (f) Best simulation obtained for δ-MnO2 at pH 3 (dBi3). In (b) the sensitivity to Na and H2O is illustrated (black line) by subtracting their contribution from the best-fit simulation shown in (a) (gray line).