Table 5. Earlier HPA results (Islam et al., 2015 ▸).

	TD theory	SQ theory
Ni—N (Å)	2.077 (4)	2.081 (4)
Ni—O (Å)	1.976 (4)	1.973 (4)
N—Ni—O (°)	89.2	89.5
i-pr
	2.94	5.42
	1.02 ± 0.02	1.00 ± 0.21
α	1.0012 ± 0.0033	1.018 ± 0.007
(Å2)	0.003 ± 0.002	0.0023 ± 0.002
(eV)	0.62 ± 0.28	4.76 ± 1.64
n-pr
	4.72	3.27
	0.93 ± 0.13	0.91 ± 0.02
α	1.008 ± 0.005	1.007 ± 0.003
(Å2)	0.002 ± 0.002	0.006 ± 0.003
(eV)	1.95 ± 1.26	2.26 ± 1.14