Electron structure of calcium and cadmium apatites

Electron structures of compounds Me-10(PO4)(6)X-2, where Me = Ca or Cd and X = F, CI, Br, OH were investigated using full potential APW+lo method. The structure and energy location of peculiarities of total and partial densities of states for cadmium apatites were established to be more sensitive to isomorphic substitution of anion fluor for chlor or bromine or OH group than for calcium ones. The P6(3)/m space were shown to be preferable for Ca-10(PO4)(6)F-2 and Ca-10(PO4)(6)CI2 than P6(3). The dependence of total energy per unit cell on the displacement along c-axis within the limits of space group P6(3) for Ca-10(PO4)(6)F-2 and Ca-10(PO4)(6)CI(2)was proven to be extremely small that justifies the lability of structure of calcium apatites with respect to this position.