Concentration fluctuations and boson peak in a binary metallic glass: A generalized collective modes study
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چکیده
It is shown that longitudinal and transverse concentration dynamic structure factors of a metallic binary glass Mg70Zn30 obtained by molecular dynamics MD simulations contain pronounced low-frequency peaks, that correspond to boson-peak modes. With a purpose of theoretical analysis of MD-derived time-correlation functions an extended approach of generalized collective modes EGCM is proposed, that permits treatment of slow collective processes in glasses. The EGCM eigenvalues are analyzed for estimation of dispersion of collective excitations in the binary glass. Low-frequency collective eigenmodes with very flat dispersion corresponding to the region of boson peak are obtained among the EGCM eigenvalues. An eigenvector analysis, performed for estimation of contributions from the collective modes to dynamic structure factors, supports strong contribution of boson-peak modes to concentration dynamic structure factors of Mg70Zn30 glass.
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تاریخ انتشار 2010