The role of pentagon–heptagon pair defect in carbon nanotube: The center of vacancy reconstruction

Abstract

We show that pentagon–heptagon (5–7) pair defects in carbon nanotube play an important role as the center of vacancy reconstruction using tight-binding molecular dynamics simulations and ab initio total energy calculations. Single vacancy defect diffuses toward and coalesces with 5–7 pair defects and the coalescence structure is reconstructed into a new and more stable 5–7 pair defect plus an adatom by an exchange mechanism. In the case of four single vacancy defects, the vacancy defects coalesce with 5–7 pair defects and form defect structures with nonhexagonal rings. Finally, these defective structures reconstruct into two new 5–7 pair defects.