Theoretical study of crossed and parallel carbon nanotube junctions and three-dimensional grid structures

[摘要] We have studied by grazing incidence x-ray diffraction the atomic positions near the surface of Cu(211) and Cu(322). For Cu(211), the relaxations are confined to the first atoms, and show a contraction of the step edge. For Cu(322), they extend deeper in the bulk. In that case, by comparing the experimental results with molecular dynamics simulation of the relaxations, we are able to extract precisely the value of the elastic dipoles equivalent to the steps that cause the long range atomic relaxations. The elastic dipole has a stretch component of 2.8x10(-10) N/at and a torque component of 3.6x10(-10) N/at. It is related to the surface stress of the (111) terraces, that is deduced to be of the order of 2 Nm(-1). Using the elasticity theory and by comparison with theoretical results, we are able to derive the elastic interaction between steps. It is found one order of magnitude higher than the value of the step interaction that has been in the past extracted from terrace width distributions.

[发布日期] 2004-11-01

[关键词] TOTAL-ENERGY CALCULATIONS;ELECTRONIC-STRUCTURE;MOLECULAR-DYNAMICS;TRANSPORT;DEFORMATION;CONDUCTANCE;ATOMS