▎ 摘　　要

The bending stiffness is a key quantity to determine mechanical bending behaviours, thermodynamical stability and even electronic transports of Graphene nanoribbons (GNRs). Using quantum mechanics lattice dynamics calculations, we characterise chirality and width dependent bending stiffness of GNRs. The results show that, in the width range (<1.6 nm) considered, out-of-plane bending stiffness of zigzag graphene nanoribbon is 17.5% larger than that of armchair graphene nanoribbon with the same width whereas their in-plane bending stiffness is very close and tend to coincide with an increase of width. These trends are attributed to differences in microscopic deformation mechanisms. We also find that, for the narrowest graphene nanoribbon, that is, polyethylene and polyacetylene, the latter has much higher out-of-plane and in-plane bending stiffness than the former.