Graphene Young’s modulus: Molecular mechanics and DFT treatments

• QM and MM methods were employed for graphene Young’s modulus estimation.
• In MM category three force fields has been investigated: AIREBO, Tresoff and EDIP.
• In QM two conventional methods have been employed: DFTB and DFT.
• We found that MM-EDIP approach is in good agreement with experiments.
• The results of EDIP potential show that Young’s modulus has the same value at both zigzag and armchair directions.

Despite of the numerous theoretical and experimental investigations on the mechanical properties of graphene as a unique nano-structured material, a precious value for this important property has not yet been presented. In the present work, the Young’s modulus of single layer graphene sheet has been investigated by using comprehensive classic as well as quantum mechanics (QM) calculations. Molecular mechanics (MM) approach with various well-defined force-fields such as AIREBO, Tresoff and EDIP potentials have been considered. In QM category, several conventional methods (DFTB and DFT-LDA/GGA) have been employed. The results show that EDIP potential method predicts more accurately the graphene Young’s modulus value compared to experimental results. Furthermore, despite the various theoretical results reported elsewhere, the EDIP potential calculations result reveals that Young’s modulus has the same value at both zigzag and armchair directions. From the results obtained here, we found that among the various MM and QM methods considered here the EDIP method seems to be the most convenient method for evaluation of both structural geometries and mechanical properties of carbon based graphene-like materials. This is because of its less computational costs accompanied with reliable results comparable with the experiments.