Due to its valency, carbon can form too many allotropes. A number of well-known forms of carbon include graphene, carbon nanotubes, capped carbon nanotubes, buckyballs, and nanocones. The remarkable mechanical properties of these carbons have attracted researchers. Numerous studies have been conducted on carbon nanotubes or graphene. In the present study, however, we applied the molecular mechanic method in order to model five forms of carbon with a uniform approach and draw a detailed comparison between the allotropes of carbon. Furthermore, we obtained Young’s modulus and natural frequencies for every form of carbon, which can be useful for researchers. The results show that increasing the diameter of the carbon nanotube will decrease its strength (decreases the Young’s modulus). Also, the capped carbon nanotube is stronger than the non-capped nanotube. This is because of the end bonds of the carbon nanotube. Also, the results show that Buckyball has extraordinary properties. Its strength is three times more than that of the carbon nanotube with the same diameter. Manuscript profile

Graphene is a two-dimensional sheet containing carbon atoms arranged as a honeycomb lattice. Graphene has been recently the subject of much interest due to its unique mechanical, thermal, and electrical properties. The experimental method for calculating the mechanical properties of graphene is complex because of its nanoscale lateral dimension, so the use of the theoretical method for calculating the properties of monolayer graphene has also received much attention recently.In this study, two-layer graphene with two different chirality angles was modeled by molecular dynamics in LAMMPS software. In summary, this research involves producing the primary structure, balancing the sample, applying the axial tensile test, and extracting the stress-strain graph from the sample. The simulated graphene has a value of 102.2*100.8 Å and an interlayer distance is 3.4 Å.The results showed that as the number of sheets increased, the amount of Young's modulus was more than that of the single-layer graphene. In addition, the fracture strength of the two-layer armchair graphene is greater than the fracture strength of the two-layer zigzag graphene. Then, by increasing the chirality angle, the fracture strength decreases. Finally, it was shown that by increasing the chirality angle in two-layer graphene from 0 ° (armchair) to 30 ° (zigzag), the Young's modulus value increases, while by increasing the chirality angle in single-layer graphene from 0 ° to 30 °, the Young's modulus does not change significantly. Manuscript profile

Graphene is a two-dimensional sheet containing carbon atoms arranged as ahoneycomb lattice. Graphene has been recently the subject of much interest dueto its unique mechanical, thermal, and electrical properties. The experimentalmethod for calculating the mechanical properties of graphene is complexbecause of its nanoscale lateral dimension, so the use of the theoretical methodfor calculating the properties of monolayer graphene has also received muchattention recently.In this study, two-layer graphene with two different chirality angles was modeledby molecular dynamics in LAMMPS software. In summary, this research involvesproducing the primary structure, balancing the sample, applying the axial tensiletest, and extracting the stress-strain graph from the sample. The simulatedgraphene has a value of 102.2*100.8 Å and an interlayer distance is 3.4 Å.The results showed that as the number of sheets increased, the amount ofYoung's modulus was more than that of the single-layer graphene. In addition,the fracture strength of the two-layer armchair graphene is greater than thefracture strength of the two-layer zigzag graphene. Then, by increasing thechirality angle, the fracture strength decreases. Finally, it was shown that byincreasing the chirality angle in two-layer graphene from 0 ° (armchair) to 30 °(zigzag), the Young's modulus value increases, while by increasing the chiralityangle in single-layer graphene from 0 ° to 30 °, the Young's modulus does notchange significantly Manuscript profile

Carbon can form numerous allotropes because of its valency. Graphene, carbon nanotubes,capped carbon nanotubes, buckyballs, and nanocones are well-known polymorphs of carbon.Remarkable mechanical properties of these carbon atoms have made them the subject of intenseresearch. Several studies have been conducted on carbon nanotubes or graphene. In the presentstudy, the molecular mechanics method was applied to model five polymorphs of carbon witha uniform approach and compare the allotropes of carbon in detail. Also, we obtained Young’smodulus and natural frequencies for every form of carbon, which can be useful for researchers.We found that an increase in the diameter of the carbon nanotube would accompany with adrop in its strength and Young’s modulus. Moreover, our results show that the capped carbonnanotube has a higher strength compared to that of the non-capped nanotube, which might bedue to the end bonds of the carbon nanotube. Finally, we identified extraordinary properties ofBuckyball including its strength, which is three times more than that of the carbon nanotubewith the same diameter Manuscript profile