We performed searches using the minimum separations from the experimental average high symmetry R3 " m structure and the ground state P2 1 /c structure separately (see Table ) and notably both cases found the P2 1 /c as the ground state structure. The distribution of structures optimized from refined search is shown in Figure . The energy ordering of the frequently mentioned LiNiO 2 structures relative to the ground state P2 1 /c structure follows: C2/m (+2.54 meV atom -1 ) < R3 " m (+28.17 meV atom -1 ), consistent with previous studies. A low energy distorted spinel-like structure (+0.31 meV atom -1 ) was encountered by AIRSS (Figure ). This structure was also identified by a previous computation study and the parent undistorted spinel-like structure was seen in low-temperature synthesis of LiCoO 2 . 61,66 Many other higher energy structures were also encountered by AIRSS, and some have lower predicted energies than the theoretical structures from the MP database. Most of the AIRSS structures have Ni in the distorted octahedral coordination and Li in octahedral or prismatic coordination. Overall, this search shows that the AIRSS is an effective tool for exploring compounds that exhibit dynamic JT distortion. ]. The Li 2 NiO 3 structure has been previously assigned to space groups C2/m with 2 f.u. and C2/c with 4 f.u., respectively. We relaxed both the C2/m and C2/c structures and they give identical energies, confirming that they are identical ground state structures (Figure ). The ground state structures can also be accessed by AIRSS. An unreported low energy dynamically stable polymorph (+1.10 meV atom -1 ) with a rock salt framework was also encountered (Figure ). AIRSS also found many other higher energy polymorphs and most of them are rock salts. The unfavourable electrostatic repulsion between the tetrahedrally coordinated Li was considered as the primary factor in affecting their stability ordering. The minimum separations between Li are 2.48 Å and 2.28 Å for the optimized structures of I-Li 2 NiO 2 and 1T-Li 2 NiO 2 , respectively (see Figure ). The latter structure has Li more closely packed, giving greater repulsion. ). The energy difference between the FM ordering and antiferromagnetic ordering (AFM) of 1T-Li 2 NiO 2 is negligible. However, the AFM ordering is always lower in energy than that of the FM ordering, which is consistent with its magnetic behaviour at low temperatures. Despite that the energy ordering at 0 K does not necessarily equate to the energy ordering observed in experiments at some finite temperatures, the discrepancies between different functionals partly originate from the inherent limitations of DFT in approximating electron interactions and the Hubbard U plays a role in biasing the results. Using the PBEsol+U functional, the predicted ground state structure is I-Li 2 NiO 2 when U = 0-4 eV, however, the 1T-Li 2 NiO 2 becomes lower in energy when U > 4 eV (Figure ). We also considered the lattice dynamics in both phases and evaluated the vibrational contribution to the constant volume Helmholtz free energy (A) using the PBEsol+U functional to predict the thermodynamic stability following: 𝐴(𝑇) = 𝑈 !"## + 𝐴 $%& (𝑇) = 𝑈 !"## + 𝑈 $%& (𝑇) -𝑇𝑆 $%& (𝑇).