Multiscale Methods for the Design of Structural Materials from First Principles: Systematic Search for New Nanostructures with Unprecedented Mechanical Properties.

摘要

We have developed first principles methods for the design of structural materials based on the concept of 'objective structures'. This concept embraces many of the structures such as nanotubes and buckyballs, as well as emerging nanosheets, nanosprings, nanorings, nanoribbons, nanocapsules and nanorods that comprise the main structures of nanotechnology. We have discovered new methods to directly compute the elastic behavior and strength of these structures, with our main applications to carbon nanotubes (of various chirality) and to graphene sheets. The main instabilities under bending and torsion have been elucidated and quantified, including the effects of twist and bending on band gap. A surprising failure behavior of carbon nanotubes in tension was discovered involving premature failure at intermediate strain rates. Finally, a proposal for the design of new testing machines for fluids at high rates of strain was given, in which the macroscopic fluid behavior can be directly related to an atomistic simulation. This simulation encompasses extreme effects such as chemical reaction and dissociation.