Modeling of Hydrogen Atom Adsorption and Diffusion in Ti3Sb Intermetallic Crystal with A15 Cubic Structure

For the first time, the adsorption of hydrogen on the (110) surface of the A15 Ti3Sb compound with a cubic structure (Cr3Si type; space group Pm3¯n) for the accumulation of hydrogen H was calculated using the density functional theory method (DFT SGGA-PBE). Taking into account the relaxation of the Ti3Sb–H system, the equilibrium positions of hydrogen on the Ti3Sb (110) surface were determined depending on the supercell size. Hydrogen adsorption on the Ti3Sb (110) surface of supercells is preferable in pit sites. All DFT calculations of the Ti3Sb–H system were performed on relaxed and optimized supercells (2 × 1 × 1, 3 × 3 × 3, and 5 × 5 × 5). Relaxation of the supercell reduced the calculated adsorption energy compared with the non-relaxed supercell. The calculated band structure and curves of local and partial densities of states of Ti3Sb–H were used to explain the interaction of hydrogen with the Ti3Sb (110) surface. The activation energy of H diffusion along the coordinates tetrahedral interstitial site → tetrahedral interstitial site (TIS–TIS) and tetrahedral interstitial site → octahedral interstitial site (TIS–OIS), along with the diffusion coefficient of H in the cubic lattice of Ti3Sb, were calculated.