Table 2. Root-mean-square Cartesian displacements (Å) for the DFT-D optimizations of (I) and (II), compared to the experimental structures.

	Energy cut-off (eV)	Optimization protocol	All-atom RMS Cartesian displacement	Non-H-atom RMS Cartesian displacement
(I)	520	Unit cell fixed	0.4309	0.3487
(I)	520	Unit cell free	0.4356	0.3561
(I)	1200	Unit cell free	0.6972	0.5749
(II)	520	Unit cell fixed	0.1494	0.1283
(II)	520	Unit cell free	0.1569	0.1329
(II)	1200	Unit cell free	0.1626	0.1282