  The three-dimensional ternary LiFeO2 compound presents various unusual
essential properties. The main features are thoroughly explored from the
first-principles calculations. The concise pictures, the critical orbital
hybridizations in Li-O and Fe-O bonds, are clearly examined through the optimal
geometric structure, the atom-dominated electronic energy spectrum, the spatial
charge densities, the spin-density distributions, the atom and
orbital-decomposed van Hove singularities, and the strong optical responses.
The unusual optical transitions cover the red-shift of the threshold frequency,
strongly optical anisotropy, various frequency-dependent absorption structures
and the most prominent plasmon mode in terms of the dielectric functions,
energy loss functions, reflectance spectra, and absorption coefficients. The
close combinations of electronic, magnetic and optical properties can identify
significant spin-polarizations, orbital hybridizations for each available
excitation channel. The developed theoretical framework will be very useful in
fully understanding the diverse phenomena of other emergent materials.
