Figure shows the resulting optimized structures of the H-terminated clusters with different twist angles, along with the 2D plot of the ESP in a plane bisecting the two hBN layers of the respective clusters. One sees from Fig. that as for the cluster with θ = 0°, the periodicity of the interlayer ESP matches that of the atomic configuration (for the crosssectional map perpendicular to the atomic planes, see Fig. ). The periodic pattern is created by the negative ESP on the N atoms and the positive ESP on the B atoms located exactly above (or below) the N atoms. As the twist angle increases from zero, the anti-aligned AA stacking (B on N or N on B) is altered to form various interlayer atomic alignments, such as N on N and B on B configurations, especially for the nearly commensurate clusters (Fig. ). From the 2D plot of the ESP shown in Fig. , one sees that such N/N (B/B) overlaps yield negative (positive) ESP. Consequently, the point where a fully eclipsed arrangement of N/N (B/B) shows the highest local negative (positive) ESP. This leads to the formation of triangular lattice-like patterns with pitches of 0.66 nm and 1.09 nm for θ = 21.6° and 13.6°, respectively, which are almost equal to those deduced from Eq.