LOW-FREQUENCY VIBRATIONS AND RELAXATIONS IN GLASSES

Using molecular dynamics a glass of soft spheres, quenched to zero tem perature, is produced and its vibrational behaviour investigated by an analysis of the normal modes. In addition to localized modes with hig h frequencies, one finds (quasi)localized modes with low frequencies w hich are centred around structural anomalies of the glass. The glass i s then heated in stages to 12.5% of the glass temperature and is allow ed to relax. In the relaxed glasses, again (quasi)localized low-freque ncy modes are found, with effective masses ranging upward from about 1 0 atomic masses as in the original glasses. The observed relaxations h ave similar effective masses and are closely related to the (quasi)loc alized vibrations.