Document Type

Article

Publication Date

12-23-2008

Abstract

First-principles density-functional calculations of the electronic structure, energy band gaps (Eg), and strain-induced band gap changes in moderate-gap single-walled (n,0) carbon nanotubes (SWNTs) are presented. It is confirmed that (n,0) SWNTs fall into two classes depending upon n mod 3=1 or 2. Eg is always lower for “mod 1” than for “mod 2” SWNTs of similar diameter. For n<10, strong curvature effects dominate Eg; from n=10 to 17, the Eg oscillations, amplified due to σ−π mixing, decrease and can be explained very well with a tight-binding model which includes trigonal warping. Under strain, the two families of semiconducting SWNTs are distinguished by equal and opposite energy shifts for these gaps. For (10,0) and (20,0) tubes, the potential surface and band gap changes are explored up to approximately ±6% strain or compression. For each strain value, full internal geometry relaxation is allowed. The calculated band gap changes are ±(115±10) meV per 1% strain, positive for the mod 1 and negative for the mod 2 family, about 10% larger than the tight-binding result of ±97 meV and twice as large as the shift predicted from a tight-binding model that includes internal sublattice relaxation.

Publisher's Statement

© 2008 American Physical Society. Article deposited here in compliance with publisher policy. Publisher's version of record: https://doi.org/10.1103/PhysRevB.78.235430

Publication Title

American Physical Society

Version

Publisher's PDF

Included in

Physics Commons

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.