Instability of higher-energy phases in simple and transition metals Original Research Article

We perform full-potential first-principles total energy calculations for several simple and transition metals along three distinct phase transformation paths, i.e. the tetragonal, trigonal and hexagonal paths. Our results show that higher-energy phases, such as the bcc structure for Al, Cu and Ti and the fcc structure for Nb, Mo, Ta and W, are always unstable with respect to one or more of transformation modes. Some local minima along the total energy profiles are found to correspond to the structures not dictated by the symmetry. We discuss the most interesting problem why a higher-energy phase may be stabilized in a pseudomorphic film.