Table 4.

Results of CASTEP calculations for Form I at 0 GPa, the convergence of the unit cell dimensions and energy with respect to the Monkhorst–Pack k-point set and separation.

k-Point Set	k-Point Separation [Å−1]	a [Å]	b [Å]	c [Å]	V [Å3]	E [eV]
1 × 1 × 2	0.12	5.329	5.329	4.670	132.60	−2422.879
2 × 2 × 2	0.09	5.562	5.562	4.606	142.50	−2422.676
2 × 2 × 3	0.08	5.558	5.558	4.629	143.00	−2422.632
3 × 3 × 3	0.07	5.559	5.559	4.629	143.04	−2422.631
3 × 3 × 4	0.06	5.559	5.559	4.631	143.11	−2422.631
4 × 4 × 4	0.05	5.557	5.557	4.629	142.94	−2422.632
4 × 4 × 5	0.04	5.558	5.558	4.630	143.02	−2422.631