P. Ravindran et al., Electronic structure, chemical bonding, and optical properties of ferroelectric and antiferroelectric NaNO2, PHYS REV B, 59(3), 1999, pp. 1776-1785
The electronic-energy band structure, site and angular momentum decomposed
density of states (DOS), and charge-density contours for ferroelectric sodi
um nitrite have been calculated using an accurate full-potential linear muf
fin-tin orbital method. The calculated total DOS is found to be in good agr
eement with experimental x-ray-photoemission spectra. From the DOS analysis
, as well as charge-density studies, we conclude that the bonding between N
a and NO2 is ionic and that the NO2 entities bond covalently. The polarized
reflectivity spectra, calculated in a large energy range up to 30 eV, are
directly compared with recent experimental spectra. The optical anisotropy
in this material is analyzed through the optical functions such as refracti
ve indices and static dielectric constants along the principal axes. Our ca
lculated band structure and optical spectra are also compared with results
obtained from the orthogonalized linear combination of atomic orbital metho
d. The role of antiferroelectric distortion on the optical property and str
uctural stability is discussed. [S0163-1829(99)00503-2].