Electronical Structure Analyses of Random Grain Boundary using Extended Semi-Empirical Molecular Orbital Method

It was experimentally clear that stress corrosion cracking (SCC) propagates mainly along random grain boundaries (GBs). In this study, an extended semi-empirical molecular orbital method was developed. This method enables us to estimate structural parameters, electronic structures, and bond energies for various large systems, which have more than 10000 atoms. Using the developed method, the bond energies of Fe atoms in Σ3 and random GBs in bulk body center cubic iron were estimated. Consequently it was confirmed that the bond strength of iron atoms in random GB became weaker than that in Σ3 GB.

Figure. Atomic distribution of random grain boundary and color map of bond energy between atoms.

Reference
T.Igarashi, T.Nakazawa, T.Tsuru, and Y.Kaji, "Atomic Bond Energy Analyses of Stainless Steel using Extended Semi-Empirical Analytical Method", The Physical Society of Japan 2008 Fall Meeting, (2008).