  The electronic band structures of the new superconducting (with T_c up to
7.7K) ternary silicides M(A_{0.5}Si_{0.5})_2 (M= Ca, Sr, Ba; A= Al, Ga) in the
AlB_2-type structure have been investigated using the full-potential LMTO
method. The calculations showed that the trend in transition temperatures
doesn't follow the changes in the density d-states at the Fermi level and
probably is associated with phonon-mode frequencies.
