“…A bulk hcp crystal contains additional 1422 and 2331 pairs, with overall ratios 9:9:3:3:3:1 for 2211, 2101, 1421, 2441, 1422 and 2331 pairs, respectively. In recent research [23][24][25], we only consider the bond pair with i = 1 for simplicity. The 1311 and 1321 bond pairs represent a disordered atomic arrangement.…”