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Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations
NaCo2O4 crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three NaCo2O4 sheets oriented in the (0, 0, 1) direction. Na1+ is bonded to six O2- atoms to form distorted NaO6 pentagonal pyramids that share corners with nine CoO6 octahedra, edges with three equivalent CoO6 octahedra, edges with six equivalent NaO6 pentagonal pyramids, and a faceface with one CoO6 octahedra. The corner-sharing octahedra tilt angles range from 8–47°. There are three shorter (2.35 Å) and three longer (2.42 Å) Na–O bond lengths. There are two inequivalent Co+3.50+ sites. In the first Co+3.50+ site, Co+3.50+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with three equivalent NaO6 pentagonal pyramids, edges with six equivalent CoO6 octahedra, and edges with three equivalent NaO6 pentagonal pyramids. There are three shorter (1.93 Å) and three longer (2.11 Å) Co–O bond lengths. In the second Co+3.50+ site, Co+3.50+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six equivalent NaO6 pentagonal pyramids, edges with six equivalent CoO6 octahedra, and a faceface with one NaO6 pentagonal pyramid. There are three shorter (1.94 Å) and three longer (2.08 Å) Co–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal non-coplanar geometry to three equivalent Co+3.50+ atoms. In the second O2- site, O2- is bonded in a 6-coordinate geometry to three equivalent Na1+ and three equivalent Co+3.50+ atoms. In the third O2- site, O2- is bonded in a trigonal non-coplanar geometry to three equivalent Co+3.50+ atoms. In the fourth O2- site, O2- is bonded to three equivalent Na1+ and three equivalent Co+3.50+ atoms to form edge-sharing ONa3Co3 octahedra.