Results of molecular dynamics simulations on vibrational properties of zeolite ZSM-5-based amorphous solids are presented. The vibrational density of states was determined for different extents of amorphization. Amorphization is found to smoothen the density of states and leads to especially large effects in the high-frequency region between 30 and 40 THz. Analysis of the contributions of atom types shows an overall dominance of oxygen, except in the frequency region between 23 and 27 THz where silicon contributes nearly equally strong. The vibrational modes are analyzed by projecting them on those of the SiO₄ and Si-O-Si subunits, and individual frequency-dependent contributions of stretching, bending, and rotation are discussed.
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Mukhopadhyay et al. (2003) studied this question.