The diffusion of self-interstitial atoms was studied by molecular dynamics simulation. The <111>-split interstitials were observed to diffuse 1-dimensionally at low temperatures, but rotated into other <111> directions as the temperature was increased. The self-interstitial diffusion was highly non-Arrhenius. Below 600K, this behavior arose from temperature-dependent correlations. At above 600K, the Arrhenius expression for thermally activated diffusion broke down when the migration barriers became small in comparison with the thermal energy. This led to Arrhenius diffusion kinetics at low temperature, and to a diffusivity which was proportional to the temperature at high temperatures.

Strongly Non-Arrhenius Self-Interstitial Diffusion in Vanadium. L.A.Zepeda-Ruiz, J.Rottler, S.Han, G.J.Ackland, R.Car, D.J.Srolovitz: Physical Review B, 2004, 70[6], 060102 (4pp)