Frequencies of breathing vibrations of nearly spherical Ar clusters calculated by molecular dynamics

Abstract

The breathing vibration of Ar _N cluster,N=13, 20, 25, 30 and 55, was investigated by use of the molecular dynamics method. The average distance$(\bar r)$ averaged over the positions of all Ar atoms with respect to the center of mass was calculated as a function of time and its frequency spectrum was derived by the Fourier transform analysis. The$\bar r$ value was proved to be a good index of the breathing vibration in comparison with the exact breathing vibration of an Ar dense sphere. The vibrational frequency thus estimated,f _MD, was found to increase with the cluster sizen as expected.