  We present the self-interaction corrected local spin density (SIC-LSD)
electronic structure and total energy calculations, leading also to valencies
of the ground state configurations, for the half-metallic double perovskites
such as Sr$_{2}$FeMoO$_{6}$, Ba$_{2}$FeMoO$_{6}$, Ca$_{2}$FeMoO$_{6}$, and
Ca$_{2}$FeReO$_{6}$. We conclude that the Fe and Mo (or Re) spin magnetic
moments are anti-parallel aligned, and the magnitude of the hybridization
induced moment on Mo does not vary much between the different compounds. The
hybridization spin magnetic moment on Re is of the order of -1.1 $\mu_{B}$,
while that on Mo is about -0.4 $\mu_{B}$, independently of the alkaline earth
element. Also the electronic structure of all the compounds studied is very
similar, with a well defined gap in the majority spin component and metallic
density of states for the minority spin component, with highly hybridized Fe,
Mo (or Re), and oxygen bands.
