First-Principles Study of Triangle Terarylene as a Possible Optical Molecular Switch

2011 ◽  
Vol 311-313 ◽  
pp. 526-529
Author(s):  
Cai Juan Xia ◽  
Han Chen Liu ◽  
Ji Xin Yin
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Molecular Switch ◽  
Optical Switches ◽  
Functional Theory ◽  
Closed Ring ◽  
Potential Applications ◽  
Homo Lumo ◽  
Non Equilibrium Green’S Function ◽  
Theoretical Results

Using non-equilibrium Green’s function formalism combined with first-principles density functional theory, we investigate the electronic transport properties of a triangle terarylene(open- and closed-ring forms) optical molecular switch. The influence of the HOMO-LUMO gaps and the spatial distributions of molecular orbitals on the quantum transport through the molecular device is discussed. Theoretical results show that the conductance of the closed-ring is 3-8 times larger than that of open-ring, which expect that this system can be one of good candidates for optical switches due to this unique advantage, and may have some potential applications in future molecular circuit.

The I-V Characteristics of the 3,3',5',5-Tetra-Tert-Butyl-Azobenzene Optical Molecular Switch: A First-Principles Study

2010 ◽  
Vol 152-153 ◽  
pp. 839-842 ◽  
Author(s):  
Cai Juan Xia ◽  
Han Chen Liu ◽  
Chang Feng Fang
Keyword(s):  
Electronic Transport ◽  
First Principles ◽  
Density Functional ◽  
Molecular Switch ◽  
Optical Switches ◽  
Functional Theory ◽  
Tert Butyl ◽  
Large Current ◽  
Homo Lumo ◽  
Theoretical Results

By applying nonequilibrium Green’s function formalism combined first-principles density functional theory, we investigate the electronic transport properties of 3,3′,5,5′-Tetra-tert-butyl-azobenzene(meta-TBA) optical molecular switch. This molecular switch comprises a meta-TBA molecule with the trans and cis forms, which can be reversed from one structure to another one upon photoexcitation. The influence of HOMO-LUMO gaps and the spatial distributions of molecular orbitals on the electronic transport through the molecular device are discussed in detail. Theoretical results show that there is a large current ratio in bias window, which suggests that this system can be one of good candidates for optical switches due to this unique advantage, and have real applications in the molecular circuit.

FIRST-PRINCIPLES STUDY ON PHOTOSWITCHING BEHAVIOR IN SINGLE MOLECULE JUNCTION

2018 ◽  
Vol 25 (03) ◽  
pp. 1850070 ◽  
Author(s):  
BAO-AN BIAN ◽  
YA-PENG ZHENG ◽  
PEI-PEI YUAN ◽  
BIN LIAO ◽  
YU-QIANG DING
Keyword(s):  
Single Molecule ◽  
First Principles ◽  
Density Functional ◽  
Molecular Switch ◽  
Functional Theory ◽  
Current Voltage ◽  
Molecule Junction ◽  
Single Molecule Junction ◽  
Close Form ◽  
Non Equilibrium Green’S Function

We carry out first-principles calculations based on density functional theory and non-equilibrium Green’s function to investigate the electronic transport properties of a diarylethene-based molecule sandwiched between two Au electrodes. This molecular switch can be reversed between open and close forms by using light stimulation. We analyze the switch behavior of these two forms through the current–voltage curves, transmission spectra and molecular projected self-consistent Hamiltonian. It has been found that the current of the close form is significantly larger than the open form, and there is a large and stable switch ratio in a wide bias window. This result indicates that this molecule can become one of the good candidates for optical molecular switch in the future.

EFFECT OF TORSION ANGLE ON THE RECTIFYING PERFORMANCE IN THE DONOR-BRIDGE-ACCEPTOR SINGLE MOLECULAR DEVICE

2012 ◽  
Vol 11 (04) ◽  
pp. 735-743 ◽  
Author(s):  
CAI-JUAN XIA ◽  
YING-TANG ZHANG ◽  
DE-SHENG LIU
Keyword(s):  
Electronic Transport ◽  
First Principles ◽  
Torsion Angle ◽  
Density Functional ◽  
Coupling Effect ◽  
Molecular Devices ◽  
Molecular Device ◽  
Functional Theory ◽  
Homo Lumo ◽  
Theoretical Results

By applying nonequilibrium Green's function formalism combined with first-principles density functional theory, we investigate the effect of torsion angle on the rectifying performance in the donor-bridge-acceptor single molecular device. The influence of HOMO–LUMO gaps and the spatial distributions of molecular orbitals on the electronic transport through the molecular device are discussed in detail. The theoretical results show that the torsion angle plays an important role in the rectifying behavior of such devices. By changing the torsion angle, namely changing the magnitude of the intermolecular coupling effect, a different rectifying behavior can be observed in these systems. The results can provide fundamental guidelines for the design of functional molecular devices to a certain extent.

scholarly journals First-Principles Study of the Contact Resistance at 2D Metal/2D Semiconductor Heterojunctions

2020 ◽  
Vol 10 (8) ◽  
pp. 2731 ◽  
Author(s):  
Michel Houssa ◽  
Ruishen Meng ◽  
Valery Afanas’ev ◽  
André Stesmans
Keyword(s):  
Contact Resistance ◽  
First Principles ◽  
Density Functional ◽  
Functional Theory ◽  
Nanoelectronic Devices ◽  
Device Applications ◽  
Mos2 Monolayers ◽  
Contact Symmetry ◽  
Non Equilibrium Green’S Function ◽  
Theoretical Results

The high contact resistance at metal/two-dimensional (2D) semiconductor junctions is a major issue for the integration of 2D materials in nanoelectronic devices. We review here recent theoretical results on the contact resistance at lateral heterojunctions between graphene or 1T-MoS2 with 2H-MoS2 monolayers. The transport properties at these junctions are computed using density functional theory and the non-equilibrium Green’s function method. The contact resistance is found to strongly depend on the edge contact symmetry/termination at graphene/2H-MoS2 contacts, varying between about 2 × 102 and 2 × 104 Ω∙μm. This large variation is correlated to the presence or absence of dangling bond defects and/or polar bonds at the interface. On the other hand, the large computed contact resistance at pristine 1T/2H-MoS2 junctions, in the range of 3–4 × 104 Ω.μm, is related to the large electron energy barrier (about 0.8 eV) at the interface. The functionalization of the metallic 1T-MoS2 contact by various adsorbates is predicted to decrease the contact resistance by about two orders of magnitude, being very promising for device applications.

The Quantum Length Dependence of Conductance in Molecular Device: An Ab Initio Study

2010 ◽  
Vol 663-665 ◽  
pp. 519-522
Author(s):  
Cai Juan Xia ◽  
Han Chen Liu ◽  
Ying Tang Zhang
Keyword(s):  
Electronic Transport ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Molecular Device ◽  
Functional Theory ◽  
Length Dependence ◽  
Molecular Conductance ◽  
Homo Lumo ◽  
Molecular Compounds

By Applying Nonequilibrium Green’s Function Formalism Combined First-Principles Density Functional Theory, we Investigate the Electronic Transport Properties of Thiophene and Furan Molecules with Different Quantum Length. the Influence of HOMO-LUMO Gaps and the Spatial Distributions of Molecular Orbitals on the Electronic Transport through the Molecular Device Are Discussed in Detail. the Results Show that the Transport Behaviors Are Determined by the Distinct Electronic Structures of the Molecular Compounds. the Length Dependence of Molecular Conductance Exhibits its Diversity for Different Molecules.

First Principles Modelling of Scroll-to-Nanotube Defect: Screw-Type Dislocation

2006 ◽  
Vol 527-529 ◽  
pp. 1583-1586 ◽  
Author(s):  
I. Suarez-Martinez ◽  
G. Savini ◽  
M.I. Heggie
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Wide Band ◽  
Interlayer Spacing ◽  
Density Functional Theory Study ◽  
Wide Band Gap ◽  
Functional Theory ◽  
Potential Applications ◽  
Wide Band Gap Semiconductors ◽  
Type Dislocation

Carbon nanotubes present interesting potential applications especially in nanoelectronics. Their electrical properties are known to be a function of their chirality. It happens that 1/3 of CNs are metallic and 2/3 are semiconductors. Narrow nanotubes are expected to be wide-band gap semiconductors. Several experimental results have shown that the thickness of a multi-wall nanotube along the axis can change, while the interlayer spacing remains fairly constant. These observations suggest the coexistence in the same tube of a scroll structure and a multi-wall nested tube. We explain this defect as a screw dislocation which by gliding transforms between these two forms. In this paper, we present a density functional theory study of the structure and energetics of screw dislocations in AA and ABC graphite, and we discuss their role in the scroll-to-nanotube transformation in multi-wall nanotubes.

An Ab Initio Study on Negative Differential Resistance in Pyrrole Trimer Molecular Device

2010 ◽  
Vol 152-153 ◽  
pp. 931-934
Author(s):  
Cai Juan Xia ◽  
Han Chen Liu ◽  
Qiu Ping Wang
Keyword(s):  
Electronic Transport ◽  
First Principles ◽  
Negative Differential Resistance ◽  
Density Functional ◽  
Differential Resistance ◽  
Resonance Peak ◽  
Molecular Device ◽  
Transmission Resonance ◽  
Functional Theory ◽  
Theoretical Results

The electronic transport properties of pyrrole trimer sandwiched between two electrodes are investigated by using nonequilibrium Green’s function formalism combined first-principles density functional theory. Theoretical results show that the system manifests negative differential resistance (NDR) behavior. A detailed analysis of the origin of negative differential resistance has been given by observing the shift in transmission resonance peak across the bias window with varying bias voltage.

Electronic Transport Properties of the Azobenzene-Based Optical Molecular Switch with Different Substituents

2011 ◽  
Vol 284-286 ◽  
pp. 816-819
Author(s):  
Cai Juan Xia ◽  
Han Chen Liu ◽  
Jing Wang
Keyword(s):  
Transport Properties ◽  
Electronic Transport ◽  
Density Functional ◽  
Molecular Switch ◽  
Functional Theory ◽  
Electronic Transport Properties ◽  
Switching Performance ◽  
Donor And Acceptor ◽  
Donor Acceptor ◽  
Theoretical Results

By applying nonequilibrium Green’s function formalism combined first-principles density functional theory, we investigate the electronic transport properties of the azobenzene -based optical molecular switch with different substituents. Theoretical results show that the donor/acceptor substituent plays an important role in the electronic transport of molecular devices. The switching performance can be improved to some extent through suitable donor and acceptor substituents.

Electronic and optical properties of AlN under pressure: DFT calculations

2017 ◽  
Vol 31 (02) ◽  
pp. 1650255
Author(s):  
Sahar Javaheri ◽  
Arash Boochani ◽  
Manuchehr Babaeipour ◽  
Sirvan Naderi
Keyword(s):  
Optical Properties ◽  
Electronic Properties ◽  
Dielectric Function ◽  
First Principles ◽  
Density Functional ◽  
Functional Theory ◽  
Zinc Blende ◽  
Rocksalt Phase ◽  
Optical And Electronic Properties ◽  
Theoretical Results

Structural, elastic, optical, and electronic properties of wurtzite (WZ), zinc-blende (ZB), and rocksalt (RS) structures of AlN are investigated using the first-principles method and within the framework of density functional theory (DFT). Lattice parameters, bulk modulus, shear modulus, Young’s modulus, and elastic constants are calculated at zero pressure and compared with other experimental and theoretical results. The wurtzite and zinc-blende structures have a transition to rocksalt phase at the pressures of 12.7 GPa and 14 GPa, respectively. The electronic properties are calculated using both GGA and EV-GGA approximations; the obtained results by EV-GGA approximation are in much better agreement with the available experimental data. The RS phase has the largest bandgap with an amount of 4.98 eV; by increasing pressure, this amount is also increased. The optical properties like dielectric function, energy loss function, refractive index, and extinction coefficient are calculated under pressure using GGA approximation. Inter-band transitions are investigated using the peaks of imaginary part of the dielectric function and these transitions mainly occur from N-2[Formula: see text] to Al-3[Formula: see text] levels. The results show that the RS structure has more different properties than the WZ and ZB structures.

WATER EFFECT ON HIGH-PRESSURE ELASTICITY OF OLIVINE, WADSLEYITE AND RINGWOODITE IN Mg2SiO4 BY FIRST-PRINCIPLES

2012 ◽  
Vol 26 (19) ◽  
pp. 1250106 ◽  
Author(s):  
WEI LIU ◽  
LI-YUN TIAN ◽  
JI-JUN ZHAO ◽  
HONG LIU ◽  
LEI LIU ◽  
...  
Keyword(s):  
High Pressure ◽  
Water Content ◽  
First Principles ◽  
Density Functional ◽  
Water Effect ◽  
Functional Theory ◽  
Seismic Properties ◽  
Hydration Effect ◽  
Theoretical Results ◽  
Water Contents

The hydration effects of water on the high-pressure elastic properties of three Mg 2 SiO 4 polymorphs have been investigated using first-principles simulation density functional theory. The effect of water incorporation was simulated by considering Mg 2 SiO 4 crystals with water contents of 0, 1.65 and 3.3 wt%. With increasing water content, the calculated bulk/shear modulus and sound velocities decrease and their pressure derivatives tend to increase. Thus the hydration effect becomes less obvious at higher pressure. The bulk velocity contrasts from olivine to wadsleyite and from wadsleyite to ringwoodite are found to decrease after water incorporation. Our theoretical results indicate that water content and partition around the phase boundaries have profound impact on the structural and seismic properties of the mantle.

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