Electronic structures of the Zr–He, Zr–H, and Zr–He–H systems

Ab initio calculations of the electronic structures of the Zr–He, Zr–H, and Zr–He–H systems have been carried out. The effect of impurities of hydrogen and helium on the electronic structure of hpc Zr has been considered. It has been found that the 1s states form a narrow band below the conduction band bottom of Zr. Unlike helium, hydrogen dissolving in zirconium does not form an additional band but it chips off a band of hybridized metal-hydrogen states from the conduction band bottom of Zr, forming a chemical bond. It has been revealed that helium forms a weak chemical bond with Zr atom as a result of hybridization of its 2$s$ states with valence states of Zr. Helium also increases the covalent component of the bond between Zr atoms in the first coordination sphere.