First-principles calculation on binding energy of an interstitial hydrogen atom around a screw dislocation in BCC iron

The binding energy of an interstitial hydrogen atom at various lattice sites around the a₀/2[111] screw dislocation core in BCC iron has been determined using the first-principles calculation. The calculation was based on the core structure of a screw dislocation with symmetric displacement field, which was obtained using the large-scale supercell containing 231 atoms and 1 x 1 x 4 k-point samplings. The binding or trapping energy of a hydrogen atom at both the t-site (tetrahedral site) and o-site (octahedral site) near a core is found to be approximately 0.2 eV. (author)