Static and dynamic properties of amorphous material derived from zeolite ZSM-5

Results of molecular dynamics simulations on structural and vibrational properties of zeolite ZSM-5 based amorphous solids are presented. Short-range ordering and connectivity is analyzed by pair-distribution functions and bond angle distributions. It is shown that the accessibility of the atoms/ions is greatly associated with the extend of amorphization. The vibrational density of states was determined for different extents of amorphization. Amorphization is found to smoothen the density of states and leads to a broadening of peaks in the high-frequency region between 30 THz and 40 THz. The vibrational modes are analyzed by projecting them on those of the SiO4 and Si-O-Si subunits and frequency-dependent contributions of stretching, bending and rotation are discussed.