Vacancy defects and the formation of local haeckelite structures in graphene from tight-binding molecular dynamics

Lee, Gun-Do; Wang, C. Z.; Yoon, Euijoon; Hwang, Nong‐Moon; Ho, Kai‐Ming

doi:10.1103/physrevb.74.245411

Cited by 83 publications

(51 citation statements)

References 22 publications

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“…This modified EDTB carbon potential has been successfully applied to investigations of various defect structures in graphene 40,41 . Details of TBMD simulation methods have been described in previous papers 38 . In TBMD simulations, the self-consistent calculations are performed by including a Hubbard-U term in TB Hamiltonian to describe correctly charge transfers in carbon atoms of dangling bonds and to prevent unrealistic overestimation of charge transfers.…”

Section: Methodsmentioning

confidence: 99%

“…TBMD simulation. The TBMD simulations are performed using a modified environment-dependent tight-binding (EDTB) carbon potential, which was modified from the original EDTB carbon potential to study carbon sp 2 bond networks 38,39 . This modified EDTB carbon potential has been successfully applied to investigations of various defect structures in graphene 40,41 .…”

Section: Methodsmentioning

confidence: 99%

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Hydrogen-free graphene edges

Lee

Robertson

et al. 2014

Nat Commun

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Graphene edges and their functionalization influence the electronic and magnetic properties of graphene nanoribbons. Theoretical calculations predict saturating graphene edges with hydrogen lower its energy and form a more stable structure. Despite the importance, experimental investigations of whether graphene edges are always hydrogen-terminated are limited. Here we study graphene edges produced by sputtering in vacuum and direct measurements of the C-C bond lengths at the edge show B86% contraction relative to the bulk. Density functional theory reveals the contraction is attributed to the formation of a triple bond and the absence of hydrogen functionalization. Time-dependent images reveal temporary attachment of a single atom to the arm-chair C-C bond in a triangular configuration, causing expansion of the bond length, which then returns back to the contracted value once the extra atom moves on and the arm-chair edge is returned. Our results provide confirmation that non-functionalized graphene edges can exist in vacuum.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Hydrogen-free graphene edges

Lee

Robertson

et al. 2014

Nat Commun

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“…The TBMD simulation is performed using the modified EDTB carbon potential, 16 which was developed from the original EDTB carbon potential. 17 This modified EDTB carbon potential has been applied to the investigation of defects in graphene and carbon nanotubes.…”

mentioning

confidence: 99%

Formation and development of dislocation in graphene

Lee

Yoon

Hwang

et al. 2013

Applied Physics Letters

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The formation and development processes of dislocation in graphene are investigated by performing tight-binding molecular dynamics (TBMD) simulation and ab initio total energy calculation. It is found that the coalescence of pentagon-heptagon (5-7) pairs with vacancy defects induces the formation of dislocation due to the separation of two 5-7 pairs. In TBMD simulations, adatoms are ejected and evaporated from graphene surface so that the dislocation is developed. It is observed that diffusing carbon atoms nearby dangling bonds help non-hexagonal rings change into stable hexagonal rings. These results might give some ideas for the control of structural properties by inducing defect structures.

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“…Recently, the EDTB carbon potential by Tang et al [13] has been further improved by Lee et al by incorporating an angle dependence factor into the repulsive energy to describe correctly the diffusion of an adatom and a vacancy in carbon nanotubes and graphene [27][28][29][30]. The modified EDTB carbon potential has described successfully the reconstruction of vacancy defects in a graphene and carbon nanotubes [27][28][29][30].…”

Section: Tbmd Simulation Of Vacancy Diffusion and Reconstruction In Gmentioning

confidence: 95%

“…The modified EDTB carbon potential has described successfully the reconstruction of vacancy defects in a graphene and carbon nanotubes [27][28][29][30].…”

Section: Tbmd Simulation Of Vacancy Diffusion and Reconstruction In Gmentioning

confidence: 98%