Abstract: SCC-DV-X method was used for the theoretical calculation of heteropoly an- ion, [SiMo_{12^v1O40]^4-,} and heteropoly blue anions,[SiMo2^v Mo10^v1O40]^6- and [SiMo4^v Mo8^v1OO40]^8-. The frontier molecular orbitals, orbital energies, Fermi 1evels, the occupied numbers of basis functions, free valences, Mulliken populations and the figure of the total density of states have been obtained. The theoretical analysis indicates that all the atoms in the anions participate in chemical reactions, but Oc and Od have higher chemical activities than other atonts, which is supported by the ex- perimental results. The heteropoly hue anions with the α-Keggin structure distort a little and the levels of valence orbitals demonstrate that [SiMo4^v Mo8^v1OO40]^8- can form a six-electron heteropoly blue anoint by accepting two electrons.

Key words: SCC-DV-X_α method, α-Keggin structure, Fermi level, Mulliken popu- lations