Intrinsic localized modes in the one-dimensional zinc-blende structure: two-body potential versus anharmonic force constant model

In this paper we examine the existence of anharmonic localized modes using a full two-body potential to describe all interactions between particles in a zinc-blende-structure material, and we make a comparison with the result s obtained with a nearest-neighbour force constant model that includes inte ractions up to quartic anharmonicity. We show that for amplitude up to a ma ximum displacement of the order of 0.25 Angstrom there are no appreciable d ifferences between the two approaches, while for the largest amplitudes the force constant model gives unphysical results.