▎ 摘　　要

The Young's modulus of graphene is investigated through the intrinsic thermal vibration in graphene which is "observed" by molecular dynamics and the results agree very well with the recent experiment [Lee et al., Science 321, 385 (2008)]. This method is further applied to show that the Young's modulus of graphene (1) increases with increasing size and saturates after a threshold value of the size; (2) increases from 0.95 to 1.1 TPa as temperature increases in the region [100, 500] K; (3) is insensitive to the isotopic disorder in the low disorder region (<5%) and decreases gradually after further increasing the disorder percentage.