Decay of BCC-structure and of bond-orientational order in a fluid (Q1089209)

The decay of an initially prepared body-centered-cubic structure and the bond-orientational order (anisotropy of the first coordination shell) are studied in a non-equilibrium molecular dynamics simulation for a fluid of 1024 particles interacting with a repulsive \(r^{-12}\) potential. Data are presented for pair-correlation functions and order parameters associated with an angle dependence described by cubic harmonics of the ranks 4, 6 and 8. These cubic pair-correlation functions and cubic order parameters are defined by the expansion of the pair-correlation function and of the bond orientational distribution function with respect to Cartesian tensors. The relaxation of the local anisotropy shows a pretransformational slowing down for densities approaching the freezing point.