Farhad KhoeiniUniversity of Zanjan · Department of Physics
Farhad Khoeini
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100
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Publications (100)
Aiming at an efficient method to determine the transport properties of a physical system, an effective and accurate band‐counting algorithm is presented to extract the transmission spectrum of a low‐dimensional system, directly from the band structure. This approach is more efficient than Hamiltonian‐dependent formalisms such as the standard Green'...
Vertical integration of dissimilar layered materials in a so-called van der Waals (vdW) heterostructure (HS) has emerged as a useful tool to engineer band alignments and interfaces. In this paper, we investigate thermoelectric currents in a phosphorene/graphene vdW nanoribbon consisting of an armchair graphene nanoribbon (AGNR) stacked on an armcha...
Nanostructures exhibit unusual properties due to the dominance of quantum mechanical effects. In addition, the geometry of a nanostructure can have a strong influence on its physical properties. Using the tight-binding and force-constant approaches with the help of the non-equilibrium Green’s function method, the transport and thermoelectric proper...
In this paper, we study the electrical conductance of a molecular bridge consisting of a graphyne ring with the chemical formula C18H6 connected to two cumulene electrodes using the tight-binding model. We then compare its conductance to a similar system in which the graphyne ring has been replaced by a benzene molecule. To do this, we first obtain...
In this work, we study the electronic and transport properties of phosphorene nanorings in two perpendicular directions (zigzag and armchair directions) in the presence of a zigzag metallic source and drain leads. Our results are based on the non-equilibrium Green’s function method and a five-parameter tight-binding approach. We investigate how sys...
In this paper, we study the structural, electronic, and quantum transport properties in the smallest fullerene, C20, and the most famous fullerene, C60, and their corresponding fulleranes, C20H20 and C60H60. The molecules are attached to cumulene and graphene nanoribbon (GNR) electrodes. We examine the factors affecting electron transport in carbon...
The Seebeck coefficient is an important quantity in determining the thermoelectric efficiency of a material. Phosphorene is a two-dimensional material with a puckered structure, which makes its properties anisotropic. In this work, a phosphorene nanodisk (PDisk) with a radius of 3.1 nm connected to two zigzag phosphorene nanoribbons is studied, num...
Due to quantum mechanical effects, nanoscale materials possess unusual and desirable properties. In this work, the electronic transport properties of four zigzag C3N/C2N hydrogen passivated heterostructures is investigated using density...
The Seebeck coefficient is an important quantity in determining the thermoelectric efficiency of a material. Phosphorene is a two-dimensional material with a puckered structure, which makes its properties anisotropic. In this work, a phosphorene nanodisk (PDisk) with a radius of 3.1 nm connected to two zigzag phosphorene nanoribbons is studied, num...
Thermoelectrics as a way to use waste heat, is essential in electronic industries, but its low performance at operational temperatures makes it inappropriate in practical applications. Tailoring graphene can change its properties. In this work, we are interested in studying the transport properties of S-shape graphene structures with the single vac...
Thermoelectrics as a way to use waste heat, is essential in electronic industries, but its low performance at operational temperatures makes it inappropriate in practical applications. Tailoring graphene can change its properties. In this work, we are interested in studying the transport properties of S-shape graphene structures with the single vac...
In a previous work, we introduced a new family of carbon cages, called fullerynes. Besides, we studied their stability by examining the vibrations of the infrared spectrum. But in this work, we intended to prepare a theoretical insight for experimental researchers for the synthesis of these carbon cages. Thus, we first examine the Raman spectra for...
The spontaneous migration and interconversion of oxygen functional groups over graphene sheet have promising high-tech applications. There is a remarkable activation energy barrier against epoxy movement over the graphene. To overcome this energy barrier, different methods have been proposed. In this paper, using first principles calculations, we s...
In this research, we investigate the electron transport in fullerene and fullerane nanocages. We study the electron transport of these systems based on the tight-binding model with the approximation of the nearest neighbors and the formulation of the Green's function. In this research, we consider the type of electrodes attached to molecules as cum...
Using the tight-binding approach and non-equilibrium Green’s function method, we investigate the electronic band structure, total electronic heat capacity (EHC), and Pauli spin susceptibility (PSS) of zigzag MoS2/MoSe2 and MoS2/WSe2 hybrid nanoribbons in the presence of transverse electric and external exchange fields. Our results show that in the...
In this research, first sila-fullerene and sila-fullerane structures have been investigated, then in terms of chemical properties, they have been compared with the corresponding carbon structures. Our findings show that silicon enters the fullerene structure only by decreasing symmetry, even at smaller sizes of fullerene geometry, it cannot form a...
Nanostructured superlattices have been the focus of many researchers due to their physical and manipulatable properties. They aim to find promising materials for new electronic and thermoelectric devices. In the present study, we investigate the thermal conductivity of two-dimensional (2D) C3N/ C2N superlattices using non-equilibrium molecular dyna...
The main contribution of this paper is to study the spin caloritronic effects in defected graphene/silicene nanoribbon (GSNR) junctions. Each step-like GSNR is subjected to the ferromagnetic exchange and local external electric fields, and their responses are determined using the nonequilibrium Green’s function (NEGF) approach. To further study the...
The main contribution of this paper is to study the spin caloritronic effects in defected graphene/silicene nanoribbon (GSNR) junctions. Each step-like GSNR is subjected to the ferromagnetic exchange and local external electric fields, and their responses are determined using the nonequilibrium Greens function (NEGF) approach. To further study the...
In this paper, we introduce new features of silicon in fullerane structures. Silicon, when placed in a fullerane structure, increases its electron affinity and electrophilicity index, compared to placement in a diamondoids structure. These nanoparticles can be used to make optical sensors to detect viral environments. In this work, we theoretically...
Nanostructured superlattices have been the focus of many researchers due to their physical and manipulatable properties. They aim to find promising materials for new electronic and thermoelectric devices. In the present study, we investigate the thermal conductivity of two-dimensional (2D) C3N/ C2N superlattices using non-equilibrium molecular dyna...
In this work, we study the thermal energy transport properties of twin graphene, which has been introduced recently as a new two-dimensional carbon nanostructure. The thermal conductivity is investigated using non-equilibrium molecular dynamics (NEMD) simulation and employing the Fourier’s law. We examine the effects of the length, temperature, and...
In this study, based on density functional theory, we propose a new branch of pseudo-fullerenes which contain triple bonds with sp hybridization. We call these new nanostructures fullerynes, according to IUPAC. We present four samples with the chemical formula of C 4n H n , and the structures derived from fulleranes. We compare the structural and e...
In this study, we introduce nano-baits that are formed based on the binding of glucose in a silicon nanoparticle. Sila-dodecahedrane has been selected among of four other famous nanostructures, due to its high stability, biocompatibility and its ability to engineer electronic features. Because of the glucose attached to nano-baits, they are attract...
Low thermal conductivity of polymers, which is one of the considerable drawbacks of commonly used composite structures, has been the focus of many researchers aiming to achieve high-performance polymer-based nanocomposites through the inclusion of highly thermally conductive fillers inside the polymer matrices. Thus, in the present study, a multisc...
The spin-dependent Seebeck effect (SDSE) and thermal spin-filtering effect (SFE) are now considered as the essential aspects of the spin caloritronics, which can efficiently explore the relationships between the spin and heat transport in the materials. However, there is still a challenge to get a thermally-induced spin current with no thermal elec...
In this paper, we investigate the effect of the perpendicular electric field on the electronic and optical properties of Zigzag bilayer silicene nanoribbons. Numerical calculations were performed in the tight-binding model. Our numerical results show, by applying a vertical electric field the metal-semiconductor phase transition occurs and the opti...
This paper aims to investigate the spin dependent transport properties in hybrid nanoribbons, using the non equilibrium Greens function method. The effects of temperature gradient between the left and right leads, the ferromagnetic exchange field, and the local external electric fields are also included. The results show that the spin up and spin d...
In this paper, we propose a combined modeling of molecular mechanics (MM) and the tight-binding (TB) approach, which enables us to study the effect of factors such as external local forces, constraints, and vacancy defects on electronic transport properties of nanomaterials. Nanostructures selected in this work are armchair graphene nanoribbons (AG...
The shortcomings of mono-component systems, e.g., the gapless nature of graphene, the lack of air-stability in phosphorene, etc. have drawn great attention toward stacked materials expected to show interesting electronic and optical properties. Using the tight-binding approach and the Green's function method, we investigate the electronic propertie...
Using electrochemical methods a profound enhancement of the capacitance of electric double-layer capacitor electrodes was reported when water molecules are strongly confined into the two-dimensional slits of titanium carbide MXene nanosheets [A. Sugahara, et. al., Nat. Commun. 2019, 10, 850]. We study the effects of hydration on the dielectric prop...
In this paper, we propose a combined modeling of molecular mechanics (MM) and the tight-binding (TB) approach, which enables us to study the effect of factors such as external local forces, constraints, and vacancy defects on electronic transport properties of nanomaterials. Nanostructures selected in this work are armchair graphene nanoribbons (AG...
The shortcomings of mono-component systems, e.g., the gapless nature of graphene, the lack of air-stability in phosphorene, etc. have drawn great attention toward stacked materials expected to show interesting electronic and optical properties. Using the tight-binding approach and the Green's function method, we investigate the electronic propertie...
In this paper, we investigate the electrical transport of two-terminal tri-
layer graphene and silicene
ake (bilayer and monolayer nanoribbons) with
ABA stacking, which is a type of arrangement for trilayer struc-
ture proposed by Bernal, in the absence and presence of nanopores and
DNA molecule by using Green's function method. The passage of the...
In this work, we study the thermal energy transport properties of twin graphene, which has been introduced recently as a new two-dimensional carbon nano structure. The thermal conductivity is investigated using non-equilibrium molecular dynamics simulation. We examine the effects of the length, temperature, and also the uni axial strain along with...
Gamma-graphyne sheet is a semiconductor with a bandgap of about 0.5 eV. For electronic applications, we need a tunable energy gap. For this purpose, we introduce a tight-binding based method which enables us to study the effects of oriented strains and also electric fields on electronic properties of nanoribbons of monolayer gamma-graphyne. Our res...
In this paper, the electrical transport of graphene and silicene nanostructures connected
to two semi-infinite graphene and silicene electrodes is investigated. In these
structures, we created nanopores and passed the DNA molecule through the nanopore. Using the Green's Function Method, two types of systems with zigzag and armchair edges in graph...
The intercalated water into nanopores exhibits anomalous properties such as ultralow dielectric constant.~Multi-scale modeling and simulations are used to investigate the dielectric properties of various crystalline two-dimensional ices and bulk ices. Although, the structural properties of two-dimensional (2D-) ices have been extensively studied, m...
The intercalated water into nanopores exhibits anomalous properties such as an ultralow dielectric constant. Multiscale modeling and simulations are used to investigate the dielectric properties of various crystalline two-dimensional ices and bulk ices. Although the structural properties of two-dimensional (2D) ices have been extensively studied, m...
We investigate the electromechanical and magnetic response of normal-zigzag phosphorene nanoribbons (nZPNRs) to the Dresselhaus spin-orbit coupling (SOC) and Rashba SOC, electric fields, exchange fields, and uniaxial strains. It is found that, when the typical exchange fields, developed by combining a ferromagnetic (FM) state with one of the antife...
We investigate thermal rectification and thermal resistance in a hybrid pillared-graphene and graphene (PGG) system by both molecular dynamics (MD) simulation and a continuum model. At first, the thermal conductivity of both pillared-graphene and graphene is calculated employing MD simulation and the Fourier's law. Our results show that the thermal...
In this study, based on density functional theory (DFT), we propose a new branch of pseudo-fullerenes which contain triple bonds with sp hybridization. We should call these new nanostructures fullerynes, according to IUPAC. We present four samples with the chemical formula of C4nHn, and structures derived from fullerenes. We compare the structural...
The low thermal conductivity of polymers has attracted great scientific challenges to achieve high-performance polymer-based nano composites through the inclusion of highly thermally conductive fillers inside the polymer matrices. In the present study, a multi scale method including three different techniques is developed to explore the impact of d...
Using non-equilibrium molecular dynamics (NEMD) simulation, we study thermal properties of the socalled
nanoporous graphene (NPG) sheet which contains a series of nanoporous in an ordered way and
was synthesized recently (Science 360 (2018), 199). The dependence of thermal conductivity on sample
size, edge chirality, and porosity concentration are...
In this works, we study the electronic structure and magnetic properties of the Pr-Ni-Bi half-Heusler systems based on density functional theory. We use the σ GGA + U scheme to consider the effects of on-site electron-electron interactions. Results show that in contrast to the rough estimation of the total magnetic moment of the unit cell, based on...
In this paper, we study spin transport properties of silicene structures such as ribbons and superlattices with the Kane–Mele model. We investigate the effects of ferromagnetic and antiferromagnetic exchange fields, vertical and transverse electric fields and defects on the band structure, density of states, as well as conductance of the system. Ou...
We study the topological properties of finite-size S-shaped graphene junctions with distinctive edge features subjected to the perpendicular magnetic field, using the tight-binding model. The quantum confinement and edge effects induced by the specific junction give rise to significant modifications in the Hofstadter spectra of the bent flakes, whe...
In this paper, we first obtain the single band tight-binding parameters of a B7 cluster in terms of matching the HOMO-LUMO levels, obtained from Density Functional Theory (DFT). Next, with the help of these parameters, we investigate the electronic and transport properties in the system formed of the B7 cluster connected to two-cumulene chains as s...
In this study, we investigate the thermal rectification and thermal resistance in the hybrid pillared-graphene and graphene (PGG) system. This is done through the classical molecular dynamics simulation (MD) and also with a continuum model. At first, the thermal conductivity of both pillared-graphene and graphene is calculated employing MD simulati...
In this paper, we study spin transport properties of silicene structures such as ribbons and superlattices with the Kane-Mele model. We investigate the effects of ferromagnetic and antiferromagnetic exchange fields, vertical and transverse electric fields and defects on the band structure, density of states as well as conductance of the system. Our...
Using non-equilibrium molecular dynamics (NEMD) simulation, we study thermal properties of the so-called nanoporous graphene (NPG) sheet which contains a series of nanoporous in an ordered way and was synthesized recently (Science 360 (2018), 199). The dependence of thermal conductivity on sample size, edge chirality, and porosity concentration are...
Thermal transport behavior in silicene nanotubes has become more important due to the application of these promising nanostructures in the engineering of next-generation nanoelectronic devices. We apply non-equilibrium molecular dynamics (NEMD) simulations to study the thermal conductivity of silicene nanotubes with different lengths and diameters....
During the fabrication process of large scale silicene, through common chemical vapor deposition (CVD) technique, polycrystalline films are quite likely to be produced, and the existence of Kapitza thermal resistance along grain boundaries could result in substantial changes of their thermal properties. In the present study, the thermal transport a...
In this paper, we study electrical properties of AB-stacked bilayer graphene-DNA hybrid nanostructure connected to two semi-infinite monolayer graphene nanoribbon leads. We investigated two types of devices with both zigzag and armchair edges and the results are evaluated by replacing the junction position. Our calculations are based on the tight-b...
Lipid-based drug delivery systems are considered as promising vehicles for hydrophobic drug compounds. Lipid distribution within the droplet can affect drug loading capacity in these carriers. However, it is extremely challenging to determine the nanostructure within these carriers through the implementation of the direct experimental methods due t...
Understanding the influence of defects on thermal conductivity of nanowires and nanomaterials is important due to its application for heat management in the nanodevices. In the present study, we investigate the influence of topological line defects on thermal conductivity of single-walled carbon nanotube (SWCNT) through molecular dynamics simulatio...
Thermal transport behavior in silicene nanotubes has become more important due to the application of these promising nanostructures in the engineering of next-generation nanoelectronic devices. We apply non-equilibrium molecular dynamics (NEMD) simulations to study the thermal conductivity of silicene nanotubes with different lengths and diameters....
Lipid-based drug delivery systems are considered as promising vehicles for hydrophobic drug compounds. Lipid distribution within the droplet can affect drug loading capacity in these carriers. It is extremely challenging to determine the nanostructure within these carriers through the implementation of the direct experimental methods due to the ult...
During the fabrication process of large scale silicene through common chemical vapor deposition (CVD) technique, polycrystalline films are quite likely to be produced, and the existence of Kapitza thermal resistance along grain boundaries could result in substantial changes of their thermal properties. In the present study, the thermal transport al...
In the last century, the health of human beings has been affected by the industrial developments. Among some problems which jeopardize
human health, we must point to environmental pollution by making noise produced by artificial machineries like cars, buses, motorcycles, airplanes, etc.
Thus, we decided to study noise pollution in Zanjan. Here, we...
Using the Tight Binding (TB) parameters extracted from Density Functional Theory (DFT) and Recursive Green's Function method (RGF), it is shown that skewed-zigzag black phosphorus (phosphorene) nanoribbons obtain large and tuneable bandgap in response to vertical and transverse electric fields. Depending on the direction of the applied field the mi...
Using density functional theory method, the linear optical absorption spectra and nonlinear optical
susceptibilities of hydrogen passivated armchair and zigzag Phosphorous Nanoribbons (aPNR and
zPNR) as well as a-phase phosphorous monolayer were calculated. It was observed that the crystallographic
direction has a strong effect on the band edge abs...
Using Density Functional Theory (DFT) method we compute linear optical absorption spectra and nonlinear optical susceptibilities of hydrogen passivated armchair and zigzag Phosphorous Nanoribbons (aPNR and zPNR) as well as α-phase phosphorous monolayer. We observe that: (a) Crystallographic direction has a strong effect on the band edge absorption...