First Principles Study of Thermal Conductance Across Cu/Graphene/Cu Nanocomposition and the Effect of Hydrogenation

2016 ◽  
Author(s):  
Yi Tao ◽  
Chenhan Liu ◽  
Juekuan Yang ◽  
Kedong Bi ◽  
Weiyu Chen ◽  
...  
Keyword(s):  
Thermal Transport ◽  
Density Functional ◽  
Thermal Conductance ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Hydrogenated Graphene ◽  
Interfacial Thermal Conductance ◽  
The Density Functional Theory ◽  
Equilibrium Separation ◽  
Transport Channels

In this work, the interfacial thermal conductance across Cu/graphene/Cu interfaces is investigated using the density functional theory (DFT) and the nonequilibrium Green’s function (NEGF) method. In order to study how hydrogenation of graphene affects thermal transport behaviors at the interfaces of Cu/graphene/Cu, we also analyze the interfacial thermal conductance across Cu/hydrogenated-graphene/Cu (Cu/H-graphene/Cu) with both double-sided and single-sided hydrogenated graphene. Our results show that, the interfacial thermal conductance across Cu/H-graphene/Cu interfaces is almost twice of the value across Cu/graphene/Cu interfaces. For Cu/H-graphene/Cu with double-sided hydrogenated graphene (Cu/DH-graphene/Cu), the hydrogen atoms between graphene and Cu layers provide additional thermal transport channels. While for Cu/H-graphene/Cu with single-sided hydrogenated graphene (Cu/SH-graphene/Cu), the hydrogen atoms not only provide additional thermal transport channels at the hydrogenated side of graphene, but also reduce the equilibrium separation between graphene and Cu layers at the non-hydrogenated side of graphene due to the transfer of massive electrons, which enhances the interface coupling between graphene and Cu layers. The phonon transmission shows that both double-sided and single-sided hydrogenation of graphene can increase the heat transport across the interface. Our calculation indicates that the interfacial thermal conductance of Cu/graphene/Cu nanocomposition can be improved by hydrogenation.

Anisotropically Nanostructured Silicon: A First-Principle Approach.

2004 ◽  
Vol 832 ◽  
Author(s):  
Yuri Bonder ◽  
Chumin Wang
Keyword(s):  
Experimental Data ◽  
Density Functional ◽  
First Principle ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Nanostructured Silicon ◽  
Plane Anisotropy ◽  
The Density Functional Theory ◽  
The Difference ◽  
Good Agreement

ABSTRACTOptical properties of birefringent porous-silicon layers are studied within the density functional theory. Starting from a (110)-oriented supercell of 32 silicon atoms, columns of atoms in directions [100] and [010] are removed and the dangling bonds are saturated with hydrogen atoms. The results show an in-plane anisotropy in the dielectric function and in the refractive index (n). The difference Δn defined as n[110] -n[001] is compared with experimental data and a good agreement is observed. Also, the possibility in determining the morphology of pores by using polarized lights is analyzed.

Gate-modulated electronic transport through a graphene nanoribbon composed of nanoribbons of different widths

2015 ◽  
Vol 14 (01) ◽  
pp. 1550005 ◽  
Author(s):  
Wen Liu ◽  
Jie Cheng ◽  
Jian-Hua Zhao ◽  
Cai-Juan Xia ◽  
De-Sheng Liu
Keyword(s):  
Integrated Circuits ◽  
Electronic Transport ◽  
Density Functional ◽  
Differential Resistance ◽  
Graphene Nanoribbon ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Effective Transport ◽  
Transport Channels ◽  
Non Equilibrium Green’S Function

Based on the non-equilibrium Green's function (NEGF) method combined with the density functional theory (DFT), we have studied the gate-modulated electronic properties of a graphene nanoribbon (GNR) which is composed of two GNRs of different widths. The results show that the charge transport is greatly modulated by the applied gate. Negative differential resistance (NDR) behaviors is found in such a system. With the increase in the gate, the NDR behaviors will disappear and reappear. Furthermore, under certain gate voltages multiple NDR behavior is found, the origin of which is attributed to the change of the number of effective transport channels and the variation of delocalization degree of the orbitals within the bias window. Interestingly, low bias NDR behavior is obtained which is desirable for integrated circuits from the point view of power consumption.

The Electronic Structure of Ga-Doped Hydrogen-Passivated Germanene: First Principle Study

2020 ◽  
Vol 833 ◽  
pp. 157-161
Author(s):  
Mauludi Ariesto Pamungkas ◽  
Husain ◽  
Achmad Kafi Shobirin ◽  
Tri Sugiono ◽  
Masruroh Masruroh
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Band Gap ◽  
Density Functional ◽  
Dft Calculation ◽  
First Principle ◽  
Hydrogen Passivation ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Hydrogenated Graphene

Germanene, which has the same structure as graphene, is an exciting novel 2D functionalized material that controls its band gap using functionalization. The effects of the Ga atom and hydrogen atoms on the structure of Ga-doped H-passivated germanene were investigated with a density functional theory (DFT) calculation. H-passivated germanene has a direct gap of 2.10 eV. Opening the band gap in the H-passivated germanene is due to transition from sp2 to sp3 orbital. Adsorption of the Ga adatom on H-site decrease the band gap to 1.38 eV. No interaction between Ga atoms and Hydrogen atoms was observed. Hence, their effects on the band structure of hydrogenated graphene were independent of each other. Our results suggest that hydrogen passivation combined with adsorption of the Ga adatoms could effectively control the band gap of germanene.

Theoretical Investigation on Electron Transport and the Effect on Thermal Transport in Graphene Ribbon

2014 ◽  
Vol 548-549 ◽  
pp. 622-625
Author(s):  
Ji Fen Wang ◽  
Hua Qing Xie
Keyword(s):  
Electron Transport ◽  
Thermal Transport ◽  
Density Functional ◽  
Graphene Ribbon ◽  
Micro Structure ◽  
Functional Theory ◽  
Electron Transmission ◽  
The Density Functional Theory ◽  
Classical Function ◽  
Transmission Pathways

The density functional theory (DFT) and nonequilibrium Green’s function methods to study the micro-structure, transmission pathways and the current density of graphene ribbon (GR). The thermal transport properties were calculated by the properties of electron transport using the classical function. The results showed that structure has strong effect on the electron transmission pathway of GR. In one side defect GR, the electron transmits mainly through the defect-free side. It shows that the more defect in GR, the more heat transferred by the electrons.

SIMULATION OF NANOSCALE ETCHING FOR NANOTUBE AND GRAPHENE DEVICES

2012 ◽  
Vol 1451 ◽  
pp. 21-24
Author(s):  
Koichi Kusakabe
Keyword(s):  
Hydrogen Atom ◽  
Density Functional ◽  
Carbon Materials ◽  
Tube Wall ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Wales Defect ◽  
The Density Functional Theory ◽  
Graphene Devices ◽  
Tungsten Tip

ABSTRACTIn order to find an efficient method to etch nano-carbon materials by hydrogenation in a controlled manner, we have studied hydrogen-atom adsorption on various deformed nanotubes using computer simulations based on the density-functional theory. The nanotube with an atomic lack is compared to a deformed tube with the Stone-Wales defect and a twisted tube wall. Similar to the known experimental etching condition for graphene, an atomic lack is effective to accumulate hydrogen atoms around the defect. Compared to the flat graphene, however, nanotube walls with curvature allow on-top adsorption of a hydrogen atom and selectivity in the hydrogenated site becomes worse. To achieve a controlled etching process, usage of a tungsten tip which realizes focused hydrogenation is proposed for natotubes and curved graphene.

scholarly journals Атомная и электронная структура реконструкций поверхности (111) в кристаллах ZnSe и CdSe

2018 ◽  
Vol 60 (1) ◽  
pp. 187
Author(s):  
В.Л. Бекенев ◽  
С.М. Зубкова
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
A Charge ◽  
Quantum Espresso ◽  
First Time ◽  
Vacuum Gap ◽  
The Ideal

AbstractThe atomic and electron structure of four variants of polar (111)-(2 × 2) surfaces in ZnSe and CdSe terminated by a cation, namely, the ideal, relaxed, reconstructed, and relaxed after reconstruction surfaces, are calculated for the first time from the first principles. The surface is simulated by a film with a thickness of 12 atomic layers and a vacuum gap of ~16 Å in the layered superlattice approximation. Four fictitious hydrogen atoms with a charge of 0.5 electrons each are added for closing dangling Se bonds on the opposite side of the film. Ab initio calculations are performed using the QUANTUM ESPRESSO software based on the density functional theory. It is shown that relaxation results in splitting of atomic layers. We calculate and analyze the band structures and total and layer-wise densities of electron states for four variants of the surface.

Design of phosphorene/graphene heterojunctions for high and tunable interfacial thermal conductance

Nanoscale ◽  
2018 ◽  
Vol 10 (42) ◽  
pp. 19854-19862 ◽  
Author(s):  
Xiangjun Liu ◽  
Junfeng Gao ◽  
Gang Zhang ◽  
Yong-Wei Zhang
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Molecular Dynamics Simulations ◽  
Density Functional ◽  
Thermal Conductance ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Atomic Structures ◽  
Interfacial Thermal Conductance ◽  
Dynamics Simulations

Using density functional theory calculations and molecular dynamics simulations, we systematically explore various possible atomic structures of phosphorene/graphene in-plane heterojunctions and their effects on interfacial thermal conductance (ITC).

Molecular Modeling of the Dimers from Cyclo-[(1R, 3S)-γ-Acc-D-Phe]3

2007 ◽  
Vol 353-358 ◽  
pp. 2244-2247
Author(s):  
Jie Cheng ◽  
Jing Chuan Zhu ◽  
Bo Liu
Keyword(s):  
Molecular Modeling ◽  
Density Functional ◽  
Cyclic Peptide ◽  
Peptide Transport ◽  
Side Chain ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Different Types ◽  
Transport Channels ◽  
Main Factor

Four kinds of dimers from cyclic peptide [-(1R, 3S)-γ-Acc-D-Phe]3 were investigated using molecular modeling based on the density functional theory (DFT), molecular mechanics (MM) and molecular dynamics (MD). The equilibrium dimer structures reveal that these dimers can be divided into two different types according to stacking formation, in which one type dimer is more stable due to the effect of side chain groups. In each type of dimers, only one can transport CHCl3. When the terminal N-substituent methyl is introduced, the transport character is reversed. Analysis of 500 ps MD trajectory suggests that the inner and terminal sizes of the dimers are the main factor that affects the transport of CHCl3. The modeling results can provide a new way for designing and synthesizing cyclic peptide transport channels.

HYDROGEN ADSORPTION ON β-TiAl (001) AND Ni/TiAl (001) SURFACES

2014 ◽  
Vol 21 (03) ◽  
pp. 1450034 ◽  
Author(s):  
A. A. KARIM MUBARAK ◽  
MAHMOUD ALELAIMI
Keyword(s):  
Density Functional ◽  
Hydrogen Adsorption ◽  
Correlation Energy ◽  
Full Potential ◽  
Generalized Gradient ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Plane Wave Method ◽  
The Density Functional Theory ◽  
Linearized Augmented Plane Wave

In this paper, we present first principles calculations of the energetic, electronic and magnetic properties of the variant termination of TiAl (001) and Ni / TiAl (001) surfaces with and without hydrogen atoms. The calculations have been performed within the density functional theory using full-potential linearized augmented plane wave method. The generalized gradient approximation (GGA) is utilized as the exchange-correlation energy. The octahedral site is the stable absorption site of H atom in the β- TiAl system. This absorption reduces the cohesive energy of β- TiAl system due to increase in the lattice constant. The surface energy for both TiAl (001) terminations is calculated. The stable adsorption site of H atoms on the variant termination of TiAl (001) surface is performed. The adsorption energy of hydrogen on Ti is more energetic than that on Al . The adsorption of H atom on both terminations of H / Ni / TiAl (001) is more preferable at the bridge site. The adsorption energies are enhanced on Ni atom due to the contraction between d- Ni bands and TiAl substrate band.

Hydrogen storage in the TiCo and TiNi alloys

2017 ◽  
Vol 28 (12) ◽  
pp. 1750148
Author(s):  
A. A. Mubarak ◽  
Farida Hamioud
Keyword(s):  
Hydrogen Storage ◽  
Optical Conductivity ◽  
Octahedral Site ◽  
Hydrogen Absorption ◽  
Density Functional ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Absorption Energy ◽  
The Density Functional Theory ◽  
Optical Applications

This is an ab initio study based on the density functional theory that uses GGA-PBE as the exchange–correlation potential. The energetic, electronic, magnetic properties, and optical conductivity of the cubic [Formula: see text] of TiCo and TiNi alloys with and without the hydrogen atom are performed. The present alloys are found to be thermodynamically stable and can be created. It can be deduced that the octahedral site has higher energetic stability absorption for the hydrogen atoms compared to the bridge and tetrahedral sites in the TiCo and TiNi alloys. The absorption energy at octahedral site is found to be 2.37[Formula: see text]eV for TiCo and 2.32[Formula: see text]eV for TiNi. Hydrogen absorption expands and brittles the host alloy. Hydrogen storage in more than one site in the host alloy is found to be energetically stable and can be formed. The chemical bonding between the constituent atoms of the present alloys is mainly ionic with some covalent bonding. The hydrogen absorption has a clear effect on the magnetic, and electrical conductivity relative to the relaxation time and optical conductivity of the present alloys. Beneficial optical applications can be assumed for the present alloys due to their high optical conductivity.

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