Constraints on the maximum ratio of cell lengths (b/a, c/a, and c/b) were imposed during the WTMetaD simulations to avoid symmetry collapse due to extremely low-dimensional structures (e.g., needle-or plate-like unit cells) caused by tilting. The limits on variable cell lengths were determined from equilibrium MD at 1000 K in the NPT ensemble, which is higher than the temperature used for the WTMetaD in this study. From the lower and upper bounds of cell deformation, the constraints on the maximum cell length ratios were set to 1.12 ≤ b/a ≤ 1.28, 0.74 ≤ c/a ≤ 0.88, and 0.60 ≤ c/b ≤ 0.75.