A multi-scale materials modelling approach was developed in order to investigate the structure, energy, mobility as well as the dynamical behavior of the neutron-induced defects in bcc transition metals and alloys for future fusion power plants. Attention was focused on quantum-mechanical effects (directional bonding, magnetism, bond-screening) in these specific materials. By using density functional theory, a database of formation energies for self-interstitial atom defects in all body-centered cubic transition metals was generated. It was found that the energies of various defect structures in non-magnetic body-centered cubic transition metals exhibited a marked systematic trend which was different to those found in ferromagnetic Fe. The new ab initio database was to be used to develop genetic and reliable interatomic potentials based upon the tight-binding approximation. These potentials were applied to studies of the core structure and glide of ½<111> screw dislocation in body-centered cubic transition metals and the magnetic properties of point defects in Fe, based upon the Stoner model. Large-scale molecular dynamics cascade simulations based upon quantum core effects were also investigated. One-dimensional analytical solutions for the strain fields of interstitial clusters were presented for comparison with the predictions of density functional theory calculations.

Multi-Scale Modelling of Defect Behavior in BCC Transition Metals and Iron Alloys for Future Fusion Power Plants. D.Nguyen-Manh, S.L.Dudarev: Materials Science and Engineering A, 2006, 423[1-2], 74-8