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Article

TAO-DFT Study on the Electronic Properties of Diamond-Shaped Graphene Nanoflakes

by 1,†, 1,† and 1,2,*
1
Department of Physics, National Taiwan University, Taipei 10617, Taiwan
2
Center for Theoretical Physics and Center for Quantum Science and Engineering, National Taiwan University, Taipei 10617, Taiwan
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Nanomaterials 2020, 10(6), 1236; https://doi.org/10.3390/nano10061236
Received: 18 May 2020 / Revised: 12 June 2020 / Accepted: 23 June 2020 / Published: 25 June 2020
(This article belongs to the Special Issue Science and Technology of Graphene)
At the nanoscale, it has been rather troublesome to properly explore the properties associated with electronic systems exhibiting a radical nature using traditional electronic structure methods. Graphene nanoflakes, which are graphene nanostructures of different shapes and sizes, are typical examples. Recently, TAO-DFT (i.e., thermally-assisted-occupation density functional theory) has been formulated to tackle such challenging problems. As a result, we adopt TAO-DFT to explore the electronic properties associated with diamond-shaped graphene nanoflakes with n = 2–15 benzenoid rings fused together at each side, designated as n-pyrenes (as they could be expanded from pyrene). For all the n values considered, n-pyrenes are ground-state singlets. With increasing the size of n-pyrene, the singlet-triplet energy gap, vertical ionization potential, and fundamental gap monotonically decrease, while the vertical electron affinity and symmetrized von Neumann entropy (which is a quantitative measure of radical nature) monotonically increase. When n increases, there is a smooth transition from the nonradical character of the smaller n-pyrenes to the increasing polyradical nature of the larger n-pyrenes. Furthermore, the latter is shown to be related to the increasing concentration of active orbitals on the zigzag edges of the larger n-pyrenes. View Full-Text
Keywords: TAO-DFT; electronic properties; graphene nanoflakes; radical nature; strong static correlation TAO-DFT; electronic properties; graphene nanoflakes; radical nature; strong static correlation
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MDPI and ACS Style

Huang, H.-J.; Seenithurai, S.; Chai, J.-D. TAO-DFT Study on the Electronic Properties of Diamond-Shaped Graphene Nanoflakes. Nanomaterials 2020, 10, 1236. https://doi.org/10.3390/nano10061236

AMA Style

Huang H-J, Seenithurai S, Chai J-D. TAO-DFT Study on the Electronic Properties of Diamond-Shaped Graphene Nanoflakes. Nanomaterials. 2020; 10(6):1236. https://doi.org/10.3390/nano10061236

Chicago/Turabian Style

Huang, Hong-Jui, Sonai Seenithurai, and Jeng-Da Chai. 2020. "TAO-DFT Study on the Electronic Properties of Diamond-Shaped Graphene Nanoflakes" Nanomaterials 10, no. 6: 1236. https://doi.org/10.3390/nano10061236

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