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تسجيل مستخدم جديدThe Raman coupling function in amorphous silica and the nature of the long wavelength excitations in disordered systems
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New Raman and incoherent neutron scattering data at various temperatures and molecular dynamic simulations in amorphous silica, are compared to obtain the Raman coupling coefficient $C(omega)$ and, in particular, its low frequency limit. This study indicates that in the $omega to 0$ limit $C(omega)$ extrapolates to a non vanishing value, giving important indications on the characteristics of the vibrational modes in disordered materials; in particular our results indicate that even in the limit of very long wavelength the local disorder implies non-regular local atomic displacements.
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