Abstract
The vibrational spectrum is investigated for the realistic models of amorphous metallic alloy Fe100-xPx. It is shown that the vibrational spectrum has two peaks. The high-frequency and low-frequency peaks are caused by the Fe-P and the Fe-Fe interaction, respectively; the former is interpreted as being due to the localised optical vibrational mode and the latter to the acoustic one. The first moment and the sound velocity in amorphous systems are reduced by about 10% in comparison with those in crystal. This is understood in terms of larger atomic volume in amorphous systems.