  We have performed ab initio LDA calculations of electronic structure of newly
discovered prototype high-temperature superconductors AFe_2As_2 (A=Ba,Sr) and
compared it with previously calculated electronic spectra of ReOFeAs
(Re=La,Ce,Pr,Nd,Sm). In all cases we obtain almost identical densities of
states in rather wide energy interval (up to 1 eV) around the Fermi level.
Energy dispersions are also very similar and almost two-dimensional in this
energy interval, leading to the same basic (minimal) model of electronic
spectra, determined mainly by Fe d-orbitals of FeAs layers. The other
constituents, such as A ions or rare earths Re (or oxygen states) are more or
less irrelevant for superconductivity. LDA Fermi surfaces for AFe_2As_2 are
also very similar to that of ReOFeAs. This makes the more simple AFe_2As_2 a
generic system to study high-temperature superconductivity in FeAs - layered
compounds.
