scholarly journals Feature-Rich Geometric and Electronic Properties of Carbon Nanoscrolls

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1372
Author(s):  
Shih-Yang Lin ◽  
Sheng-Lin Chang ◽  
Cheng-Ru Chiang ◽  
Wei-Bang Li ◽  
Hsin-Yi Liu ◽  
...  
Keyword(s):  
First Principles ◽  
Graphene Nanoribbons ◽  
Finite Size ◽  
Ribbon Width ◽  
Energy Gaps ◽  
Atomic Interactions ◽  
Essential Properties ◽  
Carbon Nanoscrolls ◽  
Spin Degeneracy ◽  
Geometric And Electronic Properties

How to form carbon nanoscrolls with non-uniform curvatures is worthy of a detailed investigation. The first-principles method is suitable for studying the combined effects due to the finite-size confinement, the edge-dependent interactions, the interlayer atomic interactions, the mechanical strains, and the magnetic configurations. The complex mechanisms can induce unusual essential properties, e.g., the optimal structures, magnetism, band gaps and energy dispersions. To reach a stable spiral profile, the requirements on the critical nanoribbon width and overlapping length will be thoroughly explored by evaluating the width-dependent scrolling energies. A comparison of formation energy between armchair and zigzag nanoscrolls is useful in understanding the experimental characterizations. The spin-up and spin-down distributions near the zigzag edges are examined for their magnetic environments. This accounts for the conservation or destruction of spin degeneracy. The various curved surfaces on a relaxed nanoscroll will create complicated multi-orbital hybridizations so that the low-lying energy dispersions and energy gaps are expected to be very sensitive to ribbon width, especially for those of armchair systems. Finally, the planar, curved, folded, and scrolled graphene nanoribbons are compared with one another to illustrate the geometry-induced diversity.

The Edge-Related Mechanical Properties of Fluorographene Nanoribbons

2015 ◽  
Vol 82 (4) ◽  
Author(s):  
Mingxing Shi ◽  
Qianhua Kan ◽  
Zhendong Sha ◽  
Guozheng Kang
Keyword(s):  
Mechanical Properties ◽  
First Principles ◽  
Graphene Nanoribbons ◽  
Layer Structure ◽  
Thickness Effect ◽  
Two Dimensional ◽  
First Principles Calculations ◽  
Ribbon Width ◽  
Residual Strains

The edge-related mechanical properties of fluorographene nanoribbons are investigated by means of first-principles calculations. It is found that for the four selected types of ribbons, edge energy quickly reaches a plateau when the width of ribbons exceeds 10 Å and then slowly increases at a rather small rate. Compressive and tensile edge stresses are found in ribbons with armchair and zigzag edges, respectively. The edge stresses are width dependent and also evidently smaller than those of graphene nanoribbons. This is understood to be due to the thickness effect of the two-dimensional (2D) layer structure of fluorographene. The in-plane stiffness and residual strains are also obtained for the selected fluorographene nanoribbons. The calculated in-plane stiffness gradually decreases as the ribbon width increases and approaches the counterpart of bulky fluorographene. Tensile and compressive residual strains led to armchair- and zigzag-edged fluorographene nanoribbons due to their different edge stresses, and both of them approach vanishing as the width increases since a larger width is equivalent to a larger stretch stiffness.

scholarly journals Geometric and Electronic Properties of Monolayer HfX2 (X = S, Se, or Te): A First-Principles Calculation

2021 ◽  
Vol 7 ◽  
Author(s):  
Thi My Duyen Huynh ◽  
Duy Khanh Nguyen ◽  
Thi Dieu Hien Nguyen ◽  
Vo Khuong Dien ◽  
Hai Duong Pham ◽  
...  
Keyword(s):  
Density Of States ◽  
First Principles ◽  
Three Dimensional ◽  
Electronic Energy ◽  
First Principles Calculation ◽  
Edge States ◽  
Essential Properties ◽  
Theoretical Predictions ◽  
Physical Phenomena ◽  
Geometric And Electronic Properties

The essential properties of monolayer HfX2 (X = S, Se, or Te) are fully explored by first-principles calculations. The optimal lattice symmetries, sublattice buckling, electronic energy spectra, and density of states are systematically investigated. Monolayer HfS2, HfSe2, and HfTe2, respectively, belong to middle-gap semiconductor, narrow-gap one and semimetal, with various energy dispersions. Moreover, the van Hove singularities (vHs) mainly arise from the band-edge states, and their special structures in the density of states strongly depend on their two or three-dimensional structures and the critical points in the energy-wave-vector space. The above-mentioned theoretical predictions are attributed to the multi-orbital hybridizations of [dx2−y2, dxy, dyz, dzx, dz2]–[s, px, py, pz] in the Hf-X chemical bonds. The diversified physical phenomena clearly indicate a high potential for applications, as observed in MoS2-related emergent materials ions.

First-principles study of the atomic structure and edge state of zigzag carbon nanoscrolls

2015 ◽  
Vol 29 (20) ◽  
pp. 1550110
Author(s):  
Hai-Xia Dong ◽  
Bai-Hua Gong ◽  
Dang-Qi Fang ◽  
Yang Zhang ◽  
Er-Hu Zhang ◽  
...  
Keyword(s):  
Atomic Structure ◽  
First Principles ◽  
Density Functional ◽  
Graphene Nanoribbons ◽  
Tight Binding ◽  
Edge State ◽  
Van Der Waals Interactions ◽  
Edge States ◽  
Tight Binding Approximation ◽  
Carbon Nanoscrolls

The atomic structure and edge state of zigzag carbon nanoscrolls (ZCNSs) are investigated using first-principles calculations based on density functional theory. The results show a non-monotonic dependence of the total energy of ZCNS on the surface curvature due to a competition between the elasticity and the van der Waals interactions in a scroll. The edge states can be tuned by using different forms of edge hydrogenation and inner radius. It is found that the edge state range of monohydrogenated ZCNSs is smaller than that of monohydrogenated zigzag-edged graphene nanoribbons (ZGNRs), which is also verified using the tight-binding approximation. With the different edge hydrogenations, ZCNSs prefer the [Formula: see text] hybridization more than the [Formula: see text] one. Our present study could suggest the possibility of adjusting the electronic properties of ZCNSs and may provide potential applications in the electronic devices.

scholarly journals On the ab initio calculation of vibrational formation entropy of point defect: the case of the silicon vacancy

2017 ◽  
Vol 8 ◽  
pp. 85505 ◽  
Author(s):  
Pia Seeberger ◽  
Julien Vidal
Keyword(s):  
Point Defect ◽  
First Principles ◽  
Defect Formation ◽  
Finite Size ◽  
Direct Calculation ◽  
Finite Size Effects ◽  
Numerical Errors ◽  
Silicon Vacancy ◽  
Size Dependent ◽  
Very High

Formation entropy of point defects is one of the last crucial elements required to fully describe the temperature dependence of point defect formation. However, while many attempts have been made to compute them for very complicated systems, very few works have been carried out such as to assess the different effects of finite size effects and precision on such quantity. Large discrepancies can be found in the literature for a system as primitive as the silicon vacancy. In this work, we have proposed a systematic study of formation entropy for silicon vacancy in its 3 stable charge states: neutral, +2 and –2 for supercells with size not below 432 atoms. Rationalization of the formation entropy is presented, highlighting importance of finite size error and the difficulty to compute such quantities due to high numerical requirement. It is proposed that the direct calculation of formation entropy of VSi using first principles methods will be plagued by very high computational workload (or large numerical errors) and finite size dependent results.

scholarly journals Rich p -type-doping phenomena in boron-substituted silicene systems

2020 ◽  
Vol 7 (12) ◽  
pp. 200723
Author(s):  
Hai Duong Pham ◽  
Wu-Pei Su ◽  
Thi Dieu Hien Nguyen ◽  
Ngoc Thanh Thuy Tran ◽  
Ming-Fa Lin
Keyword(s):  
Charge Transfer ◽  
Fermi Level ◽  
Charge Density ◽  
Electronic Properties ◽  
First Principles ◽  
Chemical Environment ◽  
First Principles Calculations ◽  
Density Distributions ◽  
Essential Properties ◽  
P Type

The essential properties of monolayer silicene greatly enriched by boron substitutions are thoroughly explored through first-principles calculations. Delicate analyses are conducted on the highly non-uniform Moire superlattices, atom-dominated band structures, charge density distributions and atom- and orbital-decomposed van Hove singularities. The hybridized 2 p z –3 p z and [2s, 2 p x , 2 p y ]–[3s, 3 p x , 3 p y ] bondings, with orthogonal relations, are obtained from the developed theoretical framework. The red-shifted Fermi level and the modified Dirac cones/ π bands/ σ bands are clearly identified under various concentrations and configurations of boron-guest atoms. Our results demonstrate that the charge transfer leads to the non-uniform chemical environment that creates diverse electronic properties.

First-principles study of electronic transport properties of graphene nanoribbons with pentagon-heptagon (5-7) line defects

2015 ◽  
Vol 1727 ◽  
Author(s):  
Yasutaka Nishida ◽  
Takashi Yoshida ◽  
Fumihiko Aiga ◽  
Yuichi Yamazaki ◽  
Hisao Miyazaki ◽  
...  
Keyword(s):  
Transport Properties ◽  
Electronic Transport ◽  
First Principles ◽  
Density Functional ◽  
Graphene Nanoribbons ◽  
Edge State ◽  
Line Defect ◽  
Electronic Transport Properties ◽  
Current Voltage ◽  
Line Defects

ABSTRACTIn this study, we investigated the influence of line defects consisting of pentagon-heptagon (5-7) pairs on the electronic transport properties of zigzag-edged and armchair-edged graphene nanoribbons (GNRs). Using the first-principles density functional theory, we study their electronic properties. To investigate their current-voltage (I-V) characteristics at low bias voltage (∼ 1 meV), we use the nonequilibrium Green’s function method. As a result, we found that the conductance of the GNRs having a connected line defect between source and drain shows better performance than that of the ideal zigzag-edged GNRs (ZGNRs). A detailed investigation of the transmission spectra and the wave function around the Fermi level reveals that the line defects arranged along the transport direction work similar to an edge state of the ZGNRs and can be an additional conduction channel. Our results suggest that such a line defect can be effective for low-resistance GNR interconnects.

Sign in / Sign up

Export Citation Format

Share Document