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

We carry out a systematic study on the microscopic morphology and its relat ionship with the signatures of the traces swept over the potential energy s urface in a soft-sphere fluid system interacting via a truncated Lennard-Jo nes potential. The state of the model system is tuned by changing its tempe rature obtained in a molecular dynamics simulation, ranging from the equili brium fluid phase to the deeply quenched supercooled states. The density an d the range of interaction are chosen so that the instantaneously barely is olated centers are present. We analyze the microscopic structural origin of the features in the instantaneous-normal-mode (INM) spectrum and search fo r evidence of state transformation. It is found that the presence of drasti c changes in the INM spectra upon entering the deep supercooled regime is a ccompanied by the reduction in the spatial connectivity. We develop a metho d to characterize the spatial configuration ration in an attempt to address the origin of the temperature-dependent changes in the spectra. (C) 2000 E lsevier Science B.V. All rights reserved.