We present a DFT study utilizing the Hubbard U correction to probe structural and magnetic disorder in $mathrm{NaO_{2}}$, primary discharge product of Na-O$_2$ batteries. We show that $mathrm{NaO_{2}}$ exhibits a large degree of rotational and magnetic disorder; a 3-body Ising Model is necessary to capture the subtle interplay of this disorder. MC simulations demonstrate that energetically favorable, FM phases near room temperature consist of alternating bands of orthogonally-oriented $mathrm{O_{2}}$ dimers. We find that bulk structures are insulating, with a subset of FM structures showing a moderate gap ($<2$ eV) in one spin channel.
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