In step II, the increasing number of introduced point defects begins forming clusters of defects, such as defect pairs or triplets. First principal calculations have shown that the defect-triplet has lower formation energy than defect-pairs . The {431} Bragg planes, marked with blue lines in the 6MR ring, start shrinking as the cumulative dose increases beyond 9 e -Å -2 and completely collapse as the cumulative dose reaches a value of 25 e -Å -2 . The formation of a defect cluster surrounding the ZnN4 tetrahedra causes the displacement of ZnN4 tetrahedra, leading to shrinkage in the {431} planes. The total displacement of {431} Bragg plane was 0.1 Å before completely collapsing, as shown in fig. ), and the rate of change in relative displacement per unit dose was 0.047 (1/e -Å -2 ) as measured from fig. (a), presented in table .