  This paper presents the comparative study of LDA calculated electronic
structure of new isostructural to iron based systems superconductors
(Sr,Ca)Pd2As2 with Tc about 1K and similar but structurally different system
BaPd2As2. Despite chemical formula looks similar to iron superconductors and
even main structural motif is the same - layers of Fe square lattices,
electronic structure of (Sr,Ca)Pd2As2 and BaPd2As2 differs from Fe(As,Se)-HTSC
completely. All these systems have essentially three dimensional Fermi surfaces
in contrast to Fe(As,Se) materials. The Fermi level is crossed by low intensive
tails of Pd-4d and As-4p states. However (Sr,Ca)Pd2As2 and BaPd2As2 materials
have rather well developed peaks of Pd-4d(x2-y2) band. Thus by doping of about
2 holes per unit cell one can increase density of states at the Fermi level by
a factor about 2.5. Since experimentally these compounds were found to be
simple BCS superconductors the hole doping may considerably increase Tc. LDA
calculated total densities of states at the Fermi level for stoichiometric
systems perfectly agree with experimental estimates signifying rather small
role of electronic correlations.
