Table 7.

Total number of function/gradient calls for geometry optimisation of bulk tungsten and interstitial defect in bulk tungsten using different preconditioning strategies. Convergence criterion was $\parallel \nabla E{\parallel }_{\infty }={1.0}^{-3}$ eV Å⁻¹.

System (# of atoms)	Bulk geometry optimisation			Interstitial geometry optimisation
	ID	Exp	FF/EAM	ID	Exp	FF/EAM
4 × 4 × 4 (64)	21	11	9	62	42	33
8 × 8 × 8 (512)	32	12	8	72	43	36
16 × 16 × 16 (4096)	56	12	9	116	46	33