scholarly journals Quantum Transport in Bridge Systems

2009 ◽  
Vol 155 ◽  
pp. 71-85 ◽  
Author(s):  
Santanu K. Maiti
Keyword(s):  
Electron Transport ◽  
Quantum Interference ◽  
Tight Binding ◽  
Molecular Wires ◽  
Function Technique ◽  
Electron Conduction ◽  
Model Calculations ◽  
Electron Transport Properties ◽  
Physical Insight ◽  
Coupling Strengths

We study electron transport properties of some molecular wires and a unconventional disordered thin film within the tight-binding framework using Green's function technique. We show that electron transport is significantly affected by quantum interference of electronic wave functions, molecule-to-electrode coupling strengths, length of the molecular wire and disorder strength. Our model calculations provide a physical insight to the behavior of electron conduction across a bridge system.

scholarly journals QUANTUM TRANSPORT THROUGH HETEROCYCLIC MOLECULES

2009 ◽  
Vol 23 (02) ◽  
pp. 177-187
Author(s):  
SANTANU K. MAITI ◽  
S. N. KARMAKAR
Keyword(s):  
Electron Transport ◽  
Transport Properties ◽  
Energy Levels ◽  
Tight Binding ◽  
Molecular Transport ◽  
Molecular Wires ◽  
Function Technique ◽  
Binding Model ◽  
Heterocyclic Molecules ◽  
Electron Transport Properties

We explore electron transport properties in molecular wires made of heterocyclic molecules (pyrrole, furan and thiophene) by using the Green's function technique. Parametric calculations are given based on the tight-binding model to describe the electron transport in these wires. It is observed that the transport properties are significantly influenced by (a) the heteroatoms in the heterocyclic molecules and (b) the molecule-to-electrodes coupling strength. Conductance (g) shows sharp resonance peaks associated with the molecular energy levels in the limit of weak molecular coupling, while they get broadened in the strong molecular coupling limit. These resonances get shifted with the change of the heteroatoms in these heterocyclic molecules. All the essential features of the electron transfer through these molecular wires become much more clearly visible from the study of our current-voltage (I-V) characteristics, and they provide several key information in the study of molecular transport.

THE EFFECT OF METAL-MOLECULE NANO-CONTACTS WITH DIFFERENT END GROUPS IN MOLECULAR ELECTRONICS

2009 ◽  
Vol 23 (30) ◽  
pp. 5657-5669 ◽  
Author(s):  
SEIFOLLAH JALILI ◽  
ABDOLHAKIM PANGH
Keyword(s):  
Electron Transport ◽  
Molecular Electronics ◽  
Atomic System ◽  
Transmission Function ◽  
Molecular Wires ◽  
Atomic Systems ◽  
Current Voltage ◽  
Electron Transport Properties ◽  
Current Voltage Characteristics ◽  
Function Density

We investigated the electron transport properties of thiophen-bithiol-based molecular wires through atomic metal–thiophen–metal systems using the first principle methods. Various metal–thiophen–metal atomic systems are constructed with different end atoms (S, Se, and Te). The electron transport of the atomic system is systematically studied by analysis of transmission function, density of states, and current–voltage characteristics of the systems.

First-Principles Study of Electron Transport Behavior through Porphyrin Molecular Wires

2010 ◽  
Vol 663-665 ◽  
pp. 616-619 ◽  
Author(s):  
Yan Wei Li ◽  
Jin Huan Yao ◽  
Xing Sheng Deng ◽  
Xiao Xi Huang
Keyword(s):  
Electron Transport ◽  
First Principles ◽  
Density Functional ◽  
Molecular Wires ◽  
Quantum Mechanical ◽  
Functional Theory ◽  
Transport Behavior ◽  
Electron Transport Properties ◽  
Ab Inito ◽  
Exponential Relation

The nonequilibrium Green’s function approach in combination with density-functional theory is used to perform ab inito quantum-mechanical calculations of the electron transport properties of porphyrin oligomers sandwiched between two gold electrodes. The results show that porphyrin oligomers are good candidates for long-range conduction wires. In particular, the decay of conductance of porphyrin oligomers does not follow the exponential relation. The electron transport behavior was analyzed from the molecular projected self-consistent Hamiltonian states and the electron transmission spectra of the molecular junctions.

scholarly journals The Bicyclo[2.2.2]octane Motif: A Class of Saturated Group 14 Quantum Interference Based Single-molecule Insulators

2018 ◽  
Author(s):  
Marc H. Garner ◽  
Mads Koerstz ◽  
Jan H. Jensen ◽  
Gemma C. Solomon
Keyword(s):  
Electron Transport ◽  
Single Molecule ◽  
High Throughput Screening ◽  
Quantum Interference ◽  
Chemical Space ◽  
Group 14 ◽  
Conjugated Molecules ◽  
Clear Cut ◽  
Electron Transport Properties ◽  
Silicon And Germanium

The electronic transmission through σ-conjugated molecules can be fully suppressed by destructive quantum interference, which makes them potential candidates for single-molecule insulators. The first molecule with clear suppression of the single-molecule conductance due to σ-interference was recently found in the form of a functionalized bicyclo[2.2.2]octasilane. Here we continue the search for potential single-molecule insulators based on saturated group 14 molecules. Using a high-throughput screening approach, we assess the electron transport properties of the bicyclo[2.2.2]octane class by systematically varying the constituent atoms between carbon, silicon, and germanium, thus exploring the full chemical space of 771 different molecules. The majority of the molecules in the bicyclo[2.2.2]octane class are found to be highly insulating molecules. Though the all-silicon molecule is a clear-cut case of σ-interference, it is not unique within its class and there are many potential molecules that we predict to be more insulating. The finding of this class of quantum interference based single-molecule insulators indicates that a broad range of highly insulating saturated group 14 molecules are likely to exist

Electron Transport Properties

2003 ◽  
Author(s):  
Toshiaki Enoki ◽  
Morinobu Endo ◽  
Masatsugu Suzuki
Keyword(s):  
Electrical Conductivity ◽  
Relaxation Time ◽  
Charge Transfer ◽  
Electron Transport ◽  
Effective Mass ◽  
Two Dimensional ◽  
Electron Conduction ◽  
Order Of Magnitude ◽  
Electron Transport Properties ◽  
Stacking Structure

In GICs, charge transfer between graphite and intercalate produces a large concentration of charge carriers, featuring an electron or hole nature in donor or acceptor GICs, respectively, as discussed in Chapter 5. GICs are therefore metallic, in contrast with the semi-metallic properties of host graphite. The typical inplane conductivity values for GICs are in the range of ~ 105 Ω−1 cm−1, which is one order of magnitude larger than the in-plane conductivity of pristine graphite (Delhaes, 1977). It is well known that the conductivity of some GICs, such as AsF5, exceeds that of copper, suggesting the properties of synthetic metals (Vogel et al., 1977). As discussed in Chapter 5, GICs have two-dimensional (2D) features in the electronic properties inherent to their stacking structure, so that electron transport is considerably anisotropic between in-plane and interplane electron conduction processes. In the in-plane process, conduction electrons, whose concentration is estimated from eq (5.9), contribute to the coherent electron conduction, and the electrical conductivity σa or resistivity ρa is described as follows (Drude formula): . . .σa =1/ρa = Neμ= Ne2τ/(m*). . . . . .(6.1). . . where N, μ, τ, and m* are the density, mobility, relaxation time, and effective mass of the conduction carriers (electrons or holes), respectively.

ELECTRON TRANSPORT THROUGH MOLECULAR CHAINS

NANO ◽  
2007 ◽  
Vol 02 (02) ◽  
pp. 103-108 ◽  
Author(s):  
SANTANU K. MAITI
Keyword(s):  
Steady State ◽  
Electron Transport ◽  
Shot Noise ◽  
Coupling Strength ◽  
Tight Binding ◽  
Function Technique ◽  
Current Fluctuations ◽  
Tight Binding Model ◽  
Binding Model ◽  
Steady State Current

We study electron transport through molecular chains attached with two nonsuperconducting electrodes by the use of Green's function technique. Here, we do parametric calculations based on the tight-binding model to characterize the electron transport through such bridge systems and see that the transport properties are significantly affected by (a) the length of the molecular chain and (b) the molecule-to-electrode coupling strength. In this context, we also discuss the steady state current fluctuations, so-called shot noise, which is a consequence of the quantization of charge and is not directly available through conductance measurements.

Tuning the structures and electron transport properties of ultrathin Cu nanowires by size and bending stress using DFT and DFTB methods

RSC Advances ◽  
2015 ◽  
Vol 5 (29) ◽  
pp. 22463-22470 ◽  
Author(s):  
C. He ◽  
G. Liu ◽  
W. X. Zhang ◽  
Z. Q. Shi ◽  
S. L. Zhou
Keyword(s):  
Electron Transport ◽  
Transport Properties ◽  
Density Functional ◽  
Tight Binding ◽  
Bending Stress ◽  
Functional Theory ◽  
Flexible Displays ◽  
Cu Nanowires ◽  
Bending Stresses ◽  
Electron Transport Properties

Electron transport properties of ultrathin Cu nanowires with diameters of 0.2–1.0 nm under different bending stresses are reported, using density functional theory and density-functional-based tight-binding approaches, for application in flexible displays and solar cells.

scholarly journals ELECTRON TRANSPORT THROUGH MULTILEVEL QUANTUM DOT

2008 ◽  
Vol 07 (01) ◽  
pp. 51-61 ◽  
Author(s):  
SANTANU K. MAITI
Keyword(s):  
Electron Transport ◽  
Transport Properties ◽  
Energy Levels ◽  
Tight Binding ◽  
Current Amplitude ◽  
Function Technique ◽  
Noise Power ◽  
Disorder Strength ◽  
Binding Model ◽  
Surface Disorder

Quantum transport properties through some multilevel quantum dots sandwiched between two metallic contacts are investigated by the use of Green's function technique. Here, we do parametric calculations, based on the tight-binding model, to study the transport properties through such bridge systems. The electron transport properties are significantly influenced by (a) the number of quantized energy levels in the dots, (b) the dot-to-electrodes coupling strength, (c) the location of the equilibrium Fermi energy E F , and (d) the surface disorder. In the limit of weak-coupling, the conductance (g) shows sharp resonance peaks associated with the quantized energy levels in the dots, while, they get substantial broadening in the strong-coupling limit. The behavior of the electron transfer through these systems becomes much more clearly visible from our study of the current–voltage (I–V) characteristics. In this context, we also describe the noise power of current fluctuations (S) and determine the Fano factor (F) which provides an important information about the electron correlation among the charge carriers. Finally, we explore a novel transport phenomenon by studying the surface disorder effect in which the current amplitude increases with the increase of the surface disorder strength in the strong disorder regime, while, the amplitude decreases in the limit of weak disorder. Such an anomalous behavior is completely opposite to that of bulk disordered system where the current amplitude always decreases with the disorder strength. It is also observed that the current amplitude strongly depends on the system size which reveals the finite quantum size effect.

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