Interface energy and electron structure for Fe/VN

The electronic and atomic structures in a model system of the semicoherent interface between bcc-Fe and nacl-VN is studied. Knowledge of interface str ucture and energetics is important for modeling of nucleation and growth in complex alloys on a thermodynamical level. Present model system is of inte rest, as Such interfaces are common in alloyed steels. For the total energy calculation a pseudopotential (PP) implementation of density-functional th eory (DFT) is used. In particular, the code includes ultrasoft PP and the s o-called generalized-gradient approximation (PW91) for the DFT exchange and correlation energy. We have calculated interface energies for supercells w ith a varying VN unit thickness and, in addition to the ideal interface, al so interfaces with N vacancies are considered. The Fe/VN interface energy i s found to be very small, although the presence of vacancies raises the ene rgy. Experimentally observed VN precipitates are very thin and the calculat ions point out features of the electron structure that make this smallness favorable.