Power Spectrum of Dual Varieties of Graphene Allotropes

Abstract

Graphene is a well-known substance with multiple functions. It has potential applications in electronic and optoelectronic devices. Two graphene sheets have been selected for the present investigation: one graphene model and another with a Stone-Wales defect model. Both the graphenes are heated at different temperatures with the help of the Nose-Hoover method up to 50000 steps. Then different potentials of each are calculated at different temperatures. It has been noted that each graphene first exhibits significant changes at various potentials before becoming consistent at a specific temperature. Similarly, the total energy of both graphenes is calculated and presented. The phonon spectral densities of both models, viz., graphene and graphene with the Stone-Wales defect, were computed with the help of linear response theory. Four major peaks are observed in each graphene and in the graphene with the Stone-Wales defect after heating at different temperatures. The presented peaks of graphene and graphene with the Stone-Wales defect are moving left with an increase in temperature. Further, the calculated peaks are decreasing in strength with an increase in temperature. Before heating the carbon, atoms are tightly bound and can move up and down with full strength since the forces of attraction will be the same from every site of atom position. After heating, the positions of the atoms change, which changes the forces of attraction at different sites. Thus, atoms are vibrating in a certain area only, or the atom breaks up from its parent.