  Ba3Al2As4 exhibits an unusual anisotropic electrical conductivity, that is,
the electrical conductivity along the chain is smaller than those along other
two directions which conflicts previous conclusion. Earlier studies on Ca5M2Pn6
showed a high electrical conductivity along the chain. The band decomposed
charge density is used to explain such unusual behavior. The results indicate
that the existence of a conductive pathway near the Fermi level is responsible
for the electrons transport. Further, the Ba-As bonding of Ba3Al2As4 is some
degree covalency which is novel for the Zintl compounds.
