Microscopic morphology and energy surface landscape in a supercooled soft-sphere system

Abstract

We carry out a systematic study on the microscopic morphology and its relationship with the signatures of the traces swept over the potential energy surface in a soft-sphere fluid system interacting via a truncated Lennard-Jones potential. The state of the model system is tuned by changing its temperature obtained in a molecular dynamics simulation, ranging from the equilibrium fluid phase to the deeply quenched supercooled states. The density and the range of interaction are chosen so that the instantaneously barely isolated centers are present. We analyze the microscopic structural origin of the features in the instantaneous-normal-mode (INM) spectrum and search for evidence of state transformation. It is found that the presence of drastic changes in the INM spectra upon entering the deep supercooled regime is accompanied by the reduction in the spatial connectivity. We develop a method to characterize the spatial configuration ration in an attempt to address the origin of the temperature-dependent changes in the spectra. (C) 2000 Elsevier Science B.V. All rights reserved.