Atomistic structures and spin density (SD) were visualized with VESTA program . To find the most favorable structures of P2-Na0.67Ni0.33Mn0.67O2 with different x values, we modeled and calculated the total Coulomb energy (Ec) of a large number of likely structures. By performing DFT-PBE calculation on the electrostatically most favorable configuration, we determined the lowest total energy structure and used that structure to study charged case as well as Mg and Sc doped system. We used the PBE optimized geometries for further DFT-PBE+U, -PBE+U+D3 (for Na0.22), and -HSE06 calculations. (details please see supporting information)