PNNL

Abstract

Density functional theory was employed to explore the energetic properties of clusters up to size 2 of Re in W. While WW is the most stable intrinsic dumbbell, ReW is more stable than ReW. However, when they are trapped by a substitutional Re (Re_s), ReW becomes more stable than ReW. In this case, the most stable configuration forms a ReWRe crowdion with the W atom in between the Re atoms. Simulations of a ReW[111] (dumbbell’s vector is from Re to W) approaching a Re_s along [111] indicate that the binding energy decreases from 0.83 eV at the first nearest neighbor (NN1) to 0.10 eV at NN3 and ~0 at NN4. In addition, while ReW and ReW are stable near a Re_s at NN1, the ReW instantaneously rotates toward ReW.