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.

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.

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.

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.

Electronic structure of the thermoelectric materials PbTe and AgPb18SbTe20 from first-principles calculations

2010 ◽  
Vol 25 (6) ◽  
pp. 1030-1036 ◽  
Author(s):  
Pengxian Lu ◽  
Zigang Shen ◽  
Xing Hu
Keyword(s):  
Band Structure ◽  
Thermoelectric Properties ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Partial Density ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Scanning Transmission ◽  
Linearized Augmented Plane Wave

To investigate the effects of substituting Ag and Sb for Pb on the thermoelectric properties of PbTe, the electronic structures of PbTe and AgPb18SbTe20 were calculated by using the linearized augmented plane wave based on the density-functional theory of the first principles. By comparing the differences in the band structure, the partial density of states (PDOS), the scanning transmission microscope, and the electron density difference for PbTe and AgPb18SbTe20, we explained the reason from the aspect of electronic structures why the thermoelectric properties of AgPb18SbTe20 could be improved significantly. Our results suggest that the excellent thermoelectric properties of AgPb18SbTe20 should be attributed in part to the narrowing of its band gap, band structure anisotropy, the much extrema and large DOS near Fermi energy, as well as the large effective mass of electrons. Moreover, the complex bonding behaviors for which the strong bonds and the weak bonds are coexisted, and the electrovalence and covalence of Pb–Te bond are mixed should also play an important role in the enhancement of the thermoelectric properties of the AgPb18SbTe20.

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.

Probing the electronic structures of Con (n = 1–5) clusters on γ-Al2O3 surfaces using first-principles calculations

2017 ◽  
Vol 19 (5) ◽  
pp. 3679-3687 ◽  
Author(s):  
Tao Yang ◽  
Masahiro Ehara
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
First Principles Calculations ◽  
Functional Theory

Using density functional theory calculations, we discussed the geometric and electronic structures and nucleation of small Co clusters on γ-Al2O3(100) and γ-Al2O3(110) surfaces.

The tuning effect of the electric field on the physical properties of some typical wurtzite semiconductors

2017 ◽  
Vol 31 (33) ◽  
pp. 1750310 ◽  
Author(s):  
Jia-Ning Li ◽  
San-Lue Hu ◽  
Hao-Yu Dong ◽  
Xiao-Ying Xu ◽  
Jia-Fu Wang ◽  
...  
Keyword(s):  
Electric Field ◽  
Physical Properties ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Great Influence ◽  
Semiconductor Materials ◽  
Functional Theory ◽  
The Stability ◽  
Wurtzite Semiconductors

Under the tuning of an external electric field, the variation of the geometric structures and the band gaps of the wurtzite semiconductors ZnS, ZnO, BeO, AlN, SiC and GaN have been investigated by the first-principles method based on density functional theory. The stability, density of states, band structures and the charge distribution have been analyzed under the electric field along (001) and (00[Formula: see text]) directions. Furthermore, the corresponding results have been compared without the electric field. According to our calculation, we find that the magnitude and the direction of the electric field have a great influence on the electronic structures of the wurtzite materials we mentioned above, which induce a phase transition from semiconductor to metal under a certain electric field. Therefore, we can regulate their physical properties of this type of semiconductor materials by tuning the magnitude and the direction of the electric field.

scholarly journals Predicting the conductance of strongly correlated molecules: the Kondo effect in perchlorotriphenylmethyl/Au junctions

Nanoscale ◽  
2018 ◽  
Vol 10 (37) ◽  
pp. 17738-17750 ◽  
Author(s):  
W. H. Appelt ◽  
A. Droghetti ◽  
L. Chioncel ◽  
M. M. Radonjić ◽  
E. Muñoz ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Perturbation Theory ◽  
First Principles ◽  
Density Functional ◽  
Kondo Effect ◽  
Strongly Correlated ◽  
Functional Theory ◽  
Molecular Conductance ◽  
Non Equilibrium

We predict the non-equilibrium molecular conductance in the Kondo regime from first principles by combining density functional theory with the renormalized super-perturbation theory.

scholarly journals A First-Principles Exploration of NaxSy Binary Phases at 1 atm and Under Pressure

Crystals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 441 ◽  
Author(s):  
Nisha Geng ◽  
Tiange Bi ◽  
Niloofar Zarifi ◽  
Yan Yan ◽  
Eva Zurek
Keyword(s):  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Elemental Sulfur ◽  
Density Functional Theory Calculations ◽  
Metastable Phases ◽  
Van Der Waals Interactions ◽  
Two Dimensional ◽  
Functional Theory ◽  
Battery Materials

Interest in Na-S compounds stems from their use in battery materials at 1 atm, as well as the potential for superconductivity under pressure. Evolutionary structure searches coupled with Density Functional Theory calculations were employed to predict stable and low-lying metastable phases of sodium poor and sodium rich sulfides at 1 atm and within 100–200 GPa. At ambient pressures, four new stable or metastable phases with unbranched sulfur motifs were predicted: Na2S3 with C 2 / c and Imm2 symmetry, C 2 -Na2S5 and C 2 -Na2S8. Van der Waals interactions were shown to affect the energy ordering of various polymorphs. At high pressure, several novel phases that contained a wide variety of zero-, one-, and two-dimensional sulfur motifs were predicted, and their electronic structures and bonding were analyzed. At 200 GPa, P 4 / m m m -Na2S8 was predicted to become superconducting below 15.5 K, which is close to results previously obtained for the β -Po phase of elemental sulfur. The structures of the most stable M3S and M4S, M = Na, phases differed from those previously reported for compounds with M = H, Li, K.

Calculation of electronic structure and mechanical properties of DO3–Fe75-xSi25Nix intermetallic compounds by first principles

2015 ◽  
Vol 29 (13) ◽  
pp. 1550087
Author(s):  
R. Ma ◽  
M. P. Wan ◽  
J. Huang ◽  
Q. Xie
Keyword(s):  
Mechanical Properties ◽  
Intermetallic Compounds ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Elastic Parameters ◽  
Functional Theory ◽  
Ni Content ◽  
The Density Functional Theory ◽  
The Difference

Based on the density functional theory (DFT), the plane-wave pseudopotential method was used to investigate the electronic structures and mechanical properties of DO 3– Fe 75-x Si 25 Ni x(x = 0, 3.125, 6.25 and 9.375) intermetallic compounds. The elastic parameters were calculated, and then the bulk modulus, shear modulus and elastic modulus were derived. The paper then focuses on the discussion of ductility and plasticity. The results show that by adding appropriate Ni to Fe 3 Si intermetallic compound can improve the ductility. But the hardness will increase when the Ni content exceeds 6.25%. Analysis of density of states (DOS) and overlap populations indicates that with the difference of the strength of bonding and activity, there were some differences of ductility among different Ni contents. The Fe 71.875 Ni 3.125 Si 25 has the lowest hardness because the covalent bonding (Fe–Si bond and Si–Ni bond) has the minimum covalent electrons.

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