The adsorption of hydrogen on B2 TiFe surfaces

We investigate the interaction of hydrogen with the B2 TiFe (001) and (110) surfaces using the full-potential linearized augmented plane wave (FLAPW) method. The changes in the electronic structures in the different B2 TiFe surfaces in comparison with the bulk ground state are analyzed. Ferromagnetic order is found in the Fe-terminated (001) surface with the magnetic moment 2.27μB, which quickly diminishes inside the film. The absorption of hydrogen onto the Fe/TiFe (001) surface results in a decrease in the magnetic moment. For the fully relaxed surfaces interacting with hydrogen, the driving bonding mechanisms for different adsorption sites are discussed. A microscopic explanation of the local surface reactivity is given. It is found that the hydrogen atoms form stronger chemical bonds with the iron atoms than with the titanium atoms in the B2 TiFe surfaces.