Structure of boron nitride nanotubes: tube closing versus chirality
نویسندگان
چکیده
The structure of boron nitride nanotubes is investigated using a generalized tight-binding molecular dynamics method. It is shown that dynamic relaxation results in a wave-like or ‘rippled’ surface in which the B atoms rotate inward and the N atoms move outward, reminiscent of the surface relaxation of the III–V semiconductors. More importantly, the three different morphologies of the tube closing with flat, conical and amorphous ends, as observed in experiments, are shown to be directly related to the tube chiralities. q 1999 Elsevier Science B.V. All rights reserved.
منابع مشابه
Structure of boron nitride nanotubules
We have used high-resolution transmission electron microscopy to resolve the @0001# projected basal plane structure and chirality relationships in boron nitride nanotubes. Evidence for tube growth along both ^101̄0& and ^112̄0& is found. Our results suggest that the ^112̄0& ~armchair! tubes form first. Subsequent growth can take the form of a ^101̄0& ~zig-zag! tube or additional armchair tubes. In ...
متن کاملFinite size effects on Raman spectrum of single-walled boron nitride nanotube
Using the spectral moments method, we present calculations of Raman active modes of Single Walled Boron Nitride Nanotube (SW-BNNT). The Spectra are computed for chiral and achiral nanotubes in terms of their diameter and length. The behaviors of low frequency Raman active modes characteristic, in terms of the tube diameter revealed that these frequencies are diameter dependent. We show that the...
متن کاملAb initio calculations of the lattice dynamics of boron nitride nanotubes
We present an extensive first-principles study of the phonons in boron nitride nanotubes using density functional perturbation theory in the local density approximation. Based on the nonsymmorphic rod-group symmetry of the tubes, the Ramanand infrared-active modes at the G point of the one-dimensional Brillouin zone are evaluated. For zigzag and chiral nanotubes, the set of infrared-active mode...
متن کاملA molecular dynamics study on the impact of defects and functionalization on the Young modulus of boron-nitride nanotubes
In this article, we examine the Young modulus of (6, m) boron-nitride nanotubes with vacancy and functionalization defects. We employ molecular dynamics simulations using the Parrinello-Rahman approach. To this end, all systems are modeled with a reactive many-body bond order Tersoff-potential with parameters due to Matsunaga et al [1], which is able to accurately describe covalent bonding. We ...
متن کاملAb initio studies of vacancies in (8,0) and (8,8) Single-walled carbon and boron nitride nanotubes.
A systematic study of vacancies in single-walled carbon nanotubes and boron nitride nanotubes was carried out. First principles calculations within the framework of density functional theory using the CASTEP code are used to optimize fully the geometries of the systems. The generalized gradient approximation is used for the exchange-correlation functional. We find that the pristine single-walle...
متن کامل