Molecular dynamics simulation of structural and dynamic properties of selenium structureswith different degrees of amorphization

Abstract

We investigated Se structures of different degrees of disorder ranging from a 5% up to a95% degree of amorphization. Starting from a trigonal crystalline structure we applieddifferent strategies to introduce disorder into the Se configurations by irradiating atomsfrom their crystalline equilibrium positions. According to the symmetry of the trigonalphase, we introduced three types of disorder, i.e. the first type where only atoms forminglayers of complete helical chains are shifted from their original positions (the thickness ofthese layers is chosen to represent the chosen degree of amorphicity), the second type whereonly atoms in planes—of respective thicknesses—lying perpendicular to the chainsare displaced and the third type where only randomly chosen atoms are shiftedfrom their crystalline equilibrium positions. After a thermal treatment of thesedisordered starting configurations, we calculated structural and dynamic properties(i.e. pair-correlation function and vibrational spectrum) and compared the results toboth the original crystalline data and results obtained from corresponding glassstructures.