The nature of electronic states and chemical bonding in lithium and potassium carbonates

In the context of the density functional theory the calculation of electron energy and space distribution in (Li_xK_1?x )₂CO₃ (x = 0, 0.5, 1) have been made employing the pseudopotential method in the basis of numerical pseudo-orbitals. The electron structure of alkali metal carbonates is shown to be essentially different from alkaline-earth ones, this being connected with the change in the charge state of both the anion as a whole and the atoms composing it. The mechanisms of chemical bond formation were investigated by the sublattice method and it was shown that its peculiarities were due to the presence of nonequivalent oxygen and cation sublattices. In Li₂CO₃, anion atoms are covalently bonded, while in LiKCO₃ and K₂CO₃ the ion constituent presents.