Electronic structure study of the dependence of the pseudogap on the icosahedral cluster size and the glue atoms

Electronic structures of crystalline Al12Mn, Al42Mn13 and Al54Mn13 are calc ulated by the tight-binding linear muffin-tin orbital method with the atomi c sphere approximation in the local density functional framework. The densi ty of states for Al12Mn shows a pseudogap at the Fermi level, whereas it is very much reduced and away from Fermi level in the case of the Al42Mn13 cr ystal. The evolution of a pseudogap near the Fermi level is observed in Al5 4Mn13 With the addition of glue atoms. Our results show that the pseudogap does not depend upon the icosahedral cluster size, for the AI-Mn system; ho wever, it is sensitive to the presence of the glue atoms.