Simulation of multi-level systems in amorphous metals

In order to gain some insight into the nature of multi-level systems the authors investigate a large number of computer generated amorphous arrangements of atoms. Using a special method they generate multiplets of amorphous equilibrium systems which have nearly the same energy and differ little in their atomic positions. Their systems, consisting of up to 500 atoms of one or two types interacting with each other by Lennard-Jones-like potentials in a pressure-free cube with periodic boundary conditions, typically have total energies differing by only 10 -4 to 10 -2 times the average binding energy per atom. In a few cases the atomic positions of two such systems were almost identical (shifted by less than 10 -2 d where d is the average atomic distance) except for a few neighbouring atoms which exhibit larger shifts ('local rearrangement'). In most cases, however, the displacement field is 'diffuse', i.e. when the system switches to the new equilibrium state many atoms exhibit small shifts of comparable size ('diffuse rearrangement' of atoms).