The simulations at 1000 K exhibit behavior in-between these extrema, thus representing an initiation of melting. We further confirmed this through calculation of the Lindemann ratio (D), i.e., the ratio of the estimated amplitude of the atomic vibrations divided by the bond length of the Co-O bonds. As shown in the inset of Figure , D increases from ~0.10 to ~0.18 when the temperature is increased from 500 to 1500 K. Generally, melting is considered to occur when D reaches a value of around 0.10-0.15, matching the values from the simulation data at 1000 K.