Hartree-Fock study of crystalline lithium nitride

The electronic structure of crystalline lithium nitride has been theoretically investigated within the Hartree-Fock approximation. The basis set comprises 28 atomic orbitals per unit cell and has been defined following strictly variational criteria. Energy data, band structure, and Mulliken populations are provided and discussed; the calculated x-ray structure factors and Compton profiles are compared with the experimental ones. All these data confirm in an unbiased way the hypothesis that nitrogen is present in ${\mathrm{Li}}_3$N as the ${\mathrm{N}}^{3-}$ ion, which does not exist as a free species, but is stabilized in the crystal by the surrounding ${\mathrm{Li}}^{+}$ ions.