Abstract:
This paper presents the results of investigation of the propagation mechanism of collective excitations in amorphous C$_{60x}$/C$_{70(1-x)}$ fullerene mixtures (with equimolar concentration $x$ = 0.50), which were obtained using molecular dynamics simulation. The critical glass-transition temperature of the system $T_c$ = 1548 K was determined from the change in the behavior of the Wendt–Abraham parameter. Spectral densities of the time correlation functions of the longitudinal $\tilde{C}_L(k,\omega)$ and transverse $\tilde{C}_T(k,\omega)$ currents for a wide region of wave numbers at temperatures below the glass-transition temperature were calculated. It was found that the dynamics of density fluctuations in amorphous C$_{60x}$/C$_{70(1-x)}$ fullerene mixtures is characterized by two dispersion acoustic-like branches of the longitudinal and transverse polarizations. The influence of poly-dispersity and form factor of the molecule of the mixture component on the microscopic dynamics of the density fluctuation in multicomponent systems was established.
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