▎ 摘　　要

This paper explores the maximum attainable numerical precision in the computation of stiffness of graphene sheet and carbon nanotubes (CNTs) using Brenner potential and Cauchy-Born rule. The extent to which the round-off and truncation errors can affect the precision of computed stiffness values is demonstrated for a finite graphene sheet and CNT. Small displacement method, local potential-fit method, and finite difference method are employed to determine the stiffness. The optimum trial displacement value to be used in these methods are determined. The corresponding maximum attainable precision in the computed stiffness is reported. Instability of the small displacement method that could result from the use of non-equilibrium configuration of graphene/CNT is highlighted. A method to circumvent this instability is proposed.