Mixed magnetic edge states in graphene quantum dots

2021 ◽  
Author(s):  
Junyao Li ◽  
Xiaofeng Liu ◽  
Lingyun Wan ◽  
Xinming Qin ◽  
Wei Hu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Density Functional ◽  
Large Scale ◽  
Graphene Quantum Dots ◽  
Density Functional Theory Calculations ◽  
Edge States ◽  
Functional Theory ◽  
Spin Polarized ◽  
Spin Arrangement ◽  
Magnetic States

Abstract Graphene quantum dots (GQDs) exhibit abundant magnetic edge states with promising applications in spintronics. Hexagonal zigzag GQDs possess a ground state with an antiferromagnetic (AFM) inter-edge coupling, followed by a metastable state with ferromagnetic (FM) inter-edge coupling. By analyzing the Hubbard model and performing large-scale spin-polarized density functional theory calculations containing thousands of atoms, we predict a series of new mixed magnetic edge states of GQDs arising from the size effect, namely mix-n, where n is the number of spin arrangement parts at each edge, with parallel spin in the same part and anti-parallel spin between adjacent parts. In particular, we demonstrate that the mix-2 state of bare GQDs (C6N2) appears when N ≥ 4 and the mix-3 state appears when N ≥ 6, where N is the number of six-membered-ring at each edge, while the mix-2 and mix-3 magnetic states appear in the hydrogenated GQDs with N = 13 and N = 15, respectively.

Density functional theory calculations of the radial breathing mode in graphene quantum dots

2019 ◽  
Vol 13 (04) ◽  
pp. 1
Author(s):  
Miguel Ojeda Martínez ◽  
Arturo Nascir Pérez Martínez ◽  
Víctor Manuel Rentería Tapia ◽  
Jose Luis Cuevas Figueroa ◽  
Duncan John Mowbray ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Quantum Dots ◽  
Density Functional ◽  
Graphene Quantum Dots ◽  
Density Functional Theory Calculations ◽  
Radial Breathing Mode ◽  
Functional Theory ◽  
Breathing Mode

scholarly journals Size Effect of Graphene Quantum Dots on Photoluminescence

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3922
Author(s):  
Ziyi Liu ◽  
Fei Li ◽  
Yi Luo ◽  
Ming Li ◽  
Guanghui Hu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Quantum Dots ◽  
Density Functional ◽  
Hydrothermal Process ◽  
Graphene Quantum Dots ◽  
Density Functional Theory Calculations ◽  
Emission Peak ◽  
One Pot ◽  
Functional Theory ◽  
Molecular Weights

High-photoluminescence (PL) graphene quantum dots (GQDs) were synthesized by a simple one-pot hydrothermal process, then separated by dialysis bags of different molecular weights. Four separated GQDs of varying sizes were obtained and displayed different PL intensities. With the decreasing size of separated GQDs, the intensity of the emission peak becomes much stronger. Finally, the GQDs of the smallest size revealed the most energetic PL intensity in four separated GQDs. The PL energy of all the separated GQDs shifted slightly, supported by density functional theory calculations.

scholarly journals Tensor-structured algorithm for reduced-order scaling large-scale Kohn–Sham density functional theory calculations

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Chih-Chuen Lin ◽  
Phani Motamarri ◽  
Vikram Gavini
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Large Scale ◽  
Density Functional Theory Calculations ◽  
System Size ◽  
Real Space ◽  
Functional Theory ◽  
Reduced Order ◽  
Separable Approximation ◽  
Tensor Basis

AbstractWe present a tensor-structured algorithm for efficient large-scale density functional theory (DFT) calculations by constructing a Tucker tensor basis that is adapted to the Kohn–Sham Hamiltonian and localized in real-space. The proposed approach uses an additive separable approximation to the Kohn–Sham Hamiltonian and an L1 localization technique to generate the 1-D localized functions that constitute the Tucker tensor basis. Numerical results show that the resulting Tucker tensor basis exhibits exponential convergence in the ground-state energy with increasing Tucker rank. Further, the proposed tensor-structured algorithm demonstrated sub-quadratic scaling with system-size for both systems with and without a gap, and involving many thousands of atoms. This reduced-order scaling has also resulted in the proposed approach outperforming plane-wave DFT implementation for systems beyond 2000 electrons.

scholarly journals Pd/Pt embedded CN monolayers as efficient catalysts for CO oxidation

2019 ◽  
Vol 21 (46) ◽  
pp. 25743-25748
Author(s):  
Yong-Chao Rao ◽  
Xiang-Mei Duan
Keyword(s):  
Density Functional Theory ◽  
Co Oxidation ◽  
Density Functional ◽  
Carbon Nitride ◽  
Density Functional Theory Calculations ◽  
Catalytic Performance ◽  
Functional Theory ◽  
Spin Polarized ◽  
Planar Carbon

The catalytic performance of Pd/Pt embedded planar carbon nitride for CO oxidation has been investigated via spin-polarized density functional theory calculations.

scholarly journals Breathing distortions in the metallic, antiferromagnetic phase of LaNiO$_3$

2018 ◽  
Vol 5 (3) ◽  
Author(s):  
Alaska Subedi
Keyword(s):  
Density Functional ◽  
Recent Observation ◽  
Quantum Critical Point ◽  
Three Dimensional ◽  
Density Functional Theory Calculations ◽  
Antiferromagnetic Phase ◽  
Functional Theory ◽  
Antiferromagnetic Ordering ◽  
Spin Polarized ◽  
Structural Fluctuations

I study the structural and magnetic instabilities in LaNiO_33 using density functional theory calculations. From the non-spin-polarized structural relaxations, I find that several structures with different Glazer tilts lie close in energy. The PnmaPnma structure is marginally favored compared to the R\overline{3}cR3¯c structure in my calculations, suggesting the presence of finite-temperature structural fluctuations and a possible proximity to a structural quantum critical point. In the spin-polarized relaxations, both structures exhibit the \uparrow\!\!0\!\!\downarrow\!\!0↑0↓0 antiferromagnetic ordering with a rock-salt arrangement of the octahedral breathing distortions. The energy gain due to the breathing distortions is larger than that due to the antiferromagnetic ordering. These phases are semimetallic with small three-dimensional Fermi pockets, which is largely consistent with the recent observation of the coexistence of antiferromagnetism and metallicity in LaNiO_33 single crystals by Guo et al. [Nat. Commun. 9, 43 (2018)].

Density functional theory calculations of atomic, electronic and thermodynamic properties of cubic LaCoO3and La1−xSrxCoO3surfaces

RSC Advances ◽  
2015 ◽  
Vol 5 (1) ◽  
pp. 760-769 ◽  
Author(s):  
Shuguang Zhang ◽  
Ning Han ◽  
Xiaoyao Tan
Keyword(s):  
Density Functional Theory ◽  
Thermodynamic Properties ◽  
Dft Calculations ◽  
Phase Diagrams ◽  
Thermodynamic Stability ◽  
Electronic Structures ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Spin Polarized

Spin-polarized DFT calculations were used to investigate the atomic, electronic structures of LaCoO3and La1−xSrxCoO3surfaces. The thermodynamic stability of these surfaces was analyzed with phase diagrams. Influence of Sr-doping was also examined.

Two dimensional MoS2 meets porphyrins via intercalation to enhance the electrocatalytic activity toward hydrogen evolution

Nanoscale ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 3780-3785 ◽  
Author(s):  
Ik Seon Kwon ◽  
In Hye Kwak ◽  
Hafiz Ghulam Abbas ◽  
Hee Won Seo ◽  
Jaemin Seo ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Electrocatalytic Activity ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Two Dimensional ◽  
Functional Theory ◽  
Spin Polarized

Mn-Porphyrin-MoS2 exhibits excellent electrocatalytic activity toward the hydrogen evolution reaction, which is supported by spin-polarized density functional theory calculations.

Intercalation of cobaltocene into WS2 nanosheets for enhanced catalytic hydrogen evolution reaction

2019 ◽  
Vol 7 (14) ◽  
pp. 8101-8106 ◽  
Author(s):  
In Hye Kwak ◽  
Hafiz Ghulam Abbas ◽  
Ik Seon Kwon ◽  
Yun Chang Park ◽  
Jaemin Seo ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Spin Polarized ◽  
Catalytic Hydrogen ◽  
Catalytic Hydrogen Evolution ◽  
Ws2 Nanosheets

Cobaltocene-intercalated WS2 nanosheets exhibit excellent catalytic activity toward the hydrogen evolution reaction, which is supported by spin-polarized density functional theory calculations.

Sign in / Sign up

Export Citation Format

Share Document