Evolution of the electron structure and excitation spectrum in palladium as a result of hydrogen absorption

The effect of hydrogen on the electron properties of palladium is investigated by a full-potential linear augmented plane wave method in the framework of the local approximation of the density-functional theory. The results show that in Pd compound with low H concentration, the peak of the density of states (DOS) lie at an energy of -7.63 eV, has a width of 0.5 eV, and a height of 0.19 eV-1. An additional band of hybridized metal-hydrogen states appears in PdHx systems in the energy region higher than 4.5 eV above the Fermi-level energy. The antibonding states localized near hydrogen atoms are localized near hydrogen atoms, while the local nature of hydrogen-palladium bonding and antibonding states limits the radius of the radiation action on the crystal to a region exceeding the distance between hydrogen atoms and neighboring Pd atoms.