Molecular dynamics simulation of structural and dynamic properties of selenium structures with different degrees of...

We investigated Se structures of different degrees of disorder ranging from a 5% up to a 95% degree of amorphization. Starting from a trigonal crystalline structure we applied different strategies to introduce disorder into the Se configurations by irradiating atoms from their crystalline equilibrium positions. According to the symmetry of the trigonal phase, we introduced three types of disorder, i.e. the first type where only atoms forming layers of complete helical chains are shifted from their original positions (the thickness of these layers is chosen to represent the chosen degree of amorphicity), the second type where only atoms in planes-of respective thicknesses-lying perpendicular to the chains are displaced and the third type where only randomly chosen atoms are shifted from their crystalline equilibrium positions. After a thermal treatment of these disordered starting configurations, we calculated structural and dynamic properties (i.e. pair-correlation function and vibrational spectrum) and compared the results to both the original crystalline data and results obtained from corresponding glass structures.