Atomistic evaluation of the point defect capture efficiency of He-V clusters in α-Fe

The displacement field around a helium-vacancy (He-V) cluster in Fe is evaluated by molecular dynamics and molecular static calculations. When the He pressure of a He-V cluster is high, Fe displacements are compressive in the direction away from the cluster, but expansive in the azimuthal angle direction. When the pressure is much higher, Fe atoms on the cluster surface are pushed off from their regular lattice positions due to high pressures and such displaced Fe atoms prefer to be localized on the same side of the cluster rather than uniformly distributed over the cluster surface. With the displacement field thus obtained, the interaction energy of point defects with the strain field of a He-V cluster is evaluated using elasticity theory. Finally, a method is developed to obtain the capture efficiency of He-V clusters for point defects.