Theoretical investigations of sp-sp2 hybridized capped graphyne nanotubes

The aim of this paper is to demonstrate a new material of a capped graphyne nanotube with sp-sp2 hybridization. In order to prove the possible existence of this structure, frequency, binding energy and kinetic stability calculations are carried out by means of density functional theory (DFT) calculation and molecular dynamics (MD) confirmation. For the understanding of the geometric structure and electronic properties, C-C bond lengths of this structure are analyzed. The energy gap between the highest occupied molecular orbital (HOMO) state and the lowest unoccupied molecular orbital (LUMO) state is calculated, and electrostatic potential (ESP) derived charges and local electron density distributions of the capped graphyne nanotube are explored. In addition, the changing trend of energy gap with the increasing electric field is used to describe the field emission properties of the structure. Finally, we calculate work functions and ionization potentials under the different electric fields to estimate potential field emission properties directly.