Molecular-dynamics computer simulations have been carried out to study the liquid and amorphous solid states for a system comprising 120 Ni and 30 P atoms. This study utilized additive central pair potentials to model the interactions. Emphasis has been placed on the geometry of the resulting potential-energy hypersurface for the system as a whole to explain temperature dependence of short-range order, and to characterize bistable degrees of freedom that dominate low-temperature properties in this, and other, amorphous solids. A small collection of transition states and associated reaction coordinates for such degrees of freedom has been numerically constructed. The corresponding atomic motions tend to be localized mainly on a small subset of the atoms, but are diverse insofar as which chemical species are involved, in barrier height and asymmetry, and in the nonlinearity of the collective reaction coordinate.

• Received 23 May 1985

DOI:https://doi.org/10.1103/PhysRevB.32.5402