EMPIRICAL MANY-BODY POTENTIAL-ENERGY FUNCTIONS FOR IRON

An empirical many-body potential energy function has been derived for iron which reproduces the phonon dispersion curves and elastic constan ts of both low-temperature (bcc) alpha-Fe and high-temperature (fcc) g amma-Fe. gamma-Fe is a metastable phase, which is calculated to lie 0. 02 eV/atom higher than alpha-Fe, with a low barrier (0.04 eV/atom) alo ng the Bain path for interconversion of the bcc and fcc phases. The '' alpha + gamma'' iron potential gives a sensible order of stabilities o f a number of two- and three-dimensional structures and a satisfactory description of the growth pattern of small iron clusters.