Zargham Bagheri

Islamic Azad University, Teheran, Tehrān, Iran

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Publications (78)130.41 Total impact

  • Zargham Bagheri
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    ABSTRACT: Potential application of single-walled C3N nanotubes was investigated as chemical sensors for acetone molecules based on the density functional theory calculations. It was found that the pristine nanotube weakly adsorbs an acetone molecule with the adsorption energy of - 9.7 kcal/mol, and its electronic properties are not sensitive to this molecule. By replacing a C atom with a Si atom, the nanotube becomes a p-type semiconductor. The adsorption energy of the acetone molecule on the Si-doped nanotube becomes much more negative (Ead=-67.4 kcal/mol). The adsorption process leads to a sizable increase in the resistance of the Si-doped tube, thereby, it can show the presence of acetone molecule, creating an electronic signal. Also, the sensitivity of these devices can be controlled by the doping level of Si atoms. By increasing the number of dopant atoms from 1 to 4, the sensitivity is gradually increased.
    No preview · Article · Oct 2015 · Physica E Low-dimensional Systems and Nanostructures
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    Maryam Nayebzadeh · Hamed Soleymanabadi · Zargham Bagheri

    Full-text · Dataset · Jul 2015
  • Ali Ahmadi Peyghan · Hamed Soleymanabadi · Zargham Bagheri
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    ABSTRACT: Using density functional theory, we investigated the interaction of an NH3 molecule with a pristine and antisite defected BN sheet (g-BN) in terms of energetic, geometric, and electronic properties. The adsorption energy of NH3 on defected g-BN was calculated to be in the range of −0.70 to −2.46 eV, which is considerably more negative than that on the pristine sheet. It was found that the adsorption of NH3 adsorption on the defected sheet may cause the release of an H2 molecule. The electronic properties of the defected BN sheet were significantly changed after the adsorption process so that its HOMO/ LUMO energy gap was changed from 3.31 to 3.60-4.97 eV. Moreover, the Fermi level of the defected sheet shifts to higher energies after the interaction, which results in reduced potential barrier of the electron emission for the sheet surface, enhancing the field emission because of the decreased work function.
    No preview · Article · Jan 2015 · Journal of the Mexican Chemical Society
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    Ali Ahmadi Peyghan · Somayeh F. Rastegar · Zargham Bagheri
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    ABSTRACT: Using density functional theory calculations, the electronic response of a ZnO nanocluster was investigated toward CO, N2, H2, O2, and F2 molecules. The change of enthalpy (at 1 atm and 273 K) upon adsorption of these molecules on the cluster was calculated to be about −168.0, −148.4, −16.3, −8.8, and −51.0 kJ/mol, respectively. It was found that this cluster can selectively detect F2 molecule among the mentioned molecules due to a significant decrease in the HOMO–LUMO gap of the cluster. Our results may help direct experimental explorations of new nanostructured materials for sensor applications. Graphical Abstract
    Full-text · Article · Dec 2014 · Monatshefte fuer Chemie/Chemical Monthly
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    ABSTRACT: We investigated geometric and electronic properties of pristine and Be2O2-decorated carbon nanocones (CNCs) in the presence and absence of an H2S molecule using density functional calculations. It was found that the H2S molecule is physisorbed on the pristine nanocone, but it presents much higher reactivity toward the decorated CNC by Be2O2 cluster. The addition of more H2S molecules has also been considered on the Be2O2/CNC surface. With the increase of H2S coverage, the interaction between H2S molecules and Be2O2/CNC becomes weaker, and up to four H2S molecules can be chemisorbed on the cone, in which adsorption energies ranged from −27.21 to −10.28 kcal/mol at the B3LYP/6-31G(d) level of theory. The results also indicate that decoration of the Be2O2 cluster on the surface of the cone induces some changes in electronic properties of the cone and its Eg is changed after the adsorption of H2S molecule.
    No preview · Article · Dec 2014 · Journal of the Iranian Chemical Society
  • Ali Ahmadi Peyghan · Hamed Soleymanabadi · Zargham Bagheri
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    ABSTRACT: We have investigated the interaction of a COS molecule with a SiC nanotube by means of density functional theory calculations. A carbon or silicon atom of the tube was replaced by an Ag atom, exploring its effect on the interaction. Replacing a carbon and a silicon atom by an Ag atom increases and decreases the adsorption energy, respectively. We found that the carbon doping by Ag atom makes the nanotube a potential chemical sensor to the gaseous COS molecules.
    No preview · Article · Dec 2014 · Journal of the Iranian Chemical Society
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    Ali Ahmadi Peyghan · Maziar Noei · Zargham Bagheri
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    ABSTRACT: The functionalization of pristine and Stone-Wales defected BC3 nanosheets with a pyrene molecule was inves- tigated using density functional theory. Frontier molecular analysis shows that the main interaction is π-π stacking, releasing energies in the range of 143.6 to 169.1 kJ mol −1 . We predicted that after the functionalization process, the elec- trical conductance of the pristine sheet may be increased. Also, it modifies the work function of the pristine sheet and, as a consequence, its field-emission current densities may significantly enhance. However, the pyrene functionalization results in little change in the electronic properties of the defected sheet.
    Full-text · Article · Dec 2014 · Journal of Molecular Modeling
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    Full-text · Dataset · Sep 2014
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    Maryam Nayebzadeh · Hamed Soleymanabadi · Zargham Bagheri
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    ABSTRACT: Adsorption of N2O on pristine and oxygen vacancy defect ZnO and BeO nanotubes was studied at the B3LYP and M06-2X levels of theory. It was found that this molecule can be used to repair the oxygen vacancy defects of these tubes. Adsorption energies of the dissociation of N2O on the defective BeO and ZnO nanotubes were calculated to be about 786.2 and 506.1 kJ/mol at the B3LYP level of theory, respectively. Molecular adsorption is barrierless, while the dissociative adsorptions have to overcome a small activation energy. Graphical Abstract
    Full-text · Article · Jun 2014 · Monatshefte fuer Chemie/Chemical Monthly
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    ABSTRACT: Density functional calculations have been performed on the structural and electronic properties of the pristine and Stone–Wales-defected (SW) carbon nanotubes (CNT) with and without the adsorption of a H2O2 molecule. H2O2 interacts with the pristine CNT weakly, releasing energy of about 2.9 kcal/mol, but it presents a bit higher reactivity toward the SW-defected CNT. However, the adsorption of the H2O2 molecule on the SW-CNT is still very weak because of its small adsorption energy, large binding distance, and small charge transfer. To enhance the reactivity, a Si–Si pair is doped at the center of a SW defect, forming a Si2-SW-CNT. In this case, a strong adsorption is found with a large E ad of 155.6 kcal/mol, and a short bond length in comparison with the SW-CNT. It also was shown that the H2O2 molecule could be reduced into the OH on the Si2-SW-CNT without significant change in the electronic properties of the tube.
    No preview · Article · Apr 2014 · Structural Chemistry
  • Zargham Bagheri · Morteza Moradi
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    ABSTRACT: The adsorption of a H2S molecule on the surface of an MgO nanotube was investigated using density functional theory. It was found that H2S molecule can be associatively adsorbed on the tube surface without any energy barrier or it can be dissociated into –H and –SH species overcoming energy barrier of 4.03–7.77 kcal/mol. The associative adsorption is site selective so that the molecule is oriented in such a way that the sulfur atom was linked to an Mg atom. The HOMO–LUMO energy gap of the tube has slightly changed upon associative adsorption, while they were significantly influenced by dissociation process. Especially, the highest occupied molecular orbital of the tube shifts to higher energies which can facilitate electron emission current from the tube surface. Also, energy gap of the tube dramatically decreased by about 0.93–1.05 eV which influences the electrical conductivity of the tube.
    No preview · Article · Apr 2014 · Structural Chemistry
  • Ali Ahmadi Peyghan · Zargham Bagheri
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    ABSTRACT: Functionalization of a boron nitride nanotube (BNNT) with 1,2 diaminobenzene (DAB) and its derivatives containing functional groups of -CN, -NO2, -OH, and -NH2 has been investigated using density functional theory in terms of energetic, electronic and geometric properties. DAB prefers to be adsorbed on B atoms of the BNNT via its amine head with the adsorption energy of -16.4 kcal/mol. Calculated density of states show that the HOMO-LUMO energy gap of the BNNT is little changed by chemical modification in the most stable states. The work function of BNNT is significantly decreased upon the functionalization with DAB molecules containing electron-donating groups of -OH and -NH2 which will facilitate the field electron emission from the tube surface.
    No preview · Article · Dec 2013 · Acta Chimica Slovenica
  • Morteza Moradi · Ali Ahmadi Peyghan · Zargham Bagheri
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    ABSTRACT: Encapsulation of several alkali and alkali earth metals inside a C30B15N15 nanocage was investigated by using density functional calculations at B3LYP and M06-2X levels of theory. It was found that the encapsulation processes are spontaneous at room temperature and 1 atm. pressure. The encapsulation favorability increases in the series: K > Na > Ca > Li > Mg > Be. Alkali earth metals influence the electronic properties of cluster relatively more compared to alkali metals. A tunable HOMO-LUMO energy gap of up to ~ 1.05 eV was predicted for C30B15N15 by the controlled encapsulation of different alkali and alkali earth metals at B3LYP/6-31G (d). Electron emission density from C30B15N15 surface will be significantly increased upon the Ca encapsulation, while in the case of Li capsulation it will be decreased based on work function calculations in our work. The thermodynamic results of B3LYP and M06-2X functionals are somewhat similar, while those of electronic properties are significantly different.
    No preview · Article · Jun 2013 · Synthetic Metals
  • Mansoureh Pashangpour · Zargham Bagheri · Vahid Ghaffari
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    ABSTRACT: In this paper, a first-principle investigation of the electronic properties of graphene on hexagonal boron nitride substrate, and of one-sided and two-sided fully saturated hydrocarbons with C-H formula derived from a single sheet of graphene, tablelike and chairlike graphane, are presented within density functional theory (DFT). We obtain the most stable orientation of graphene on the substrate, the adsorption energy, the charge transfer and density of states (DOS) for these systems. We discuss the changes in the density of states as well as the extent of charge transfer, band gap and finally quantum conductivity and current for graphene due to the presence of the substrate and H atoms. We show that the band gap of 64 meV induced by the BN substrate can greatly improve the electrical characteristics of graphene-based field effect transistors (FETs) and its on/off ratio and decreases the minimum conductance by a factor three. We identify that the substrate is acting as a donor for graphene layer and graphene is acting as an acceptor with respect to H atoms after saturation with hydrogen. We show that graphene on h-BN substrate has higher on/off ratio respect to pristine graphene and higher conductance respect to tablelike graphane.
    No preview · Article · Jun 2013 · Physics of Condensed Matter
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    ABSTRACT: We have investigated the adsorption of hydrogen fluoride (HF) on the AlN nanotube surface using density functional theory in terms of energetic, structural and electronic properties. By overcoming energy barriers of 27.90–52.30 kcal/mol, HF molecule is dissociated into H and F species on the tube surface and its molecular structure is not preserved after the adsorption process. Dissociation energies have been calculated to be �52.57 and �70.10 kcal/mol. The process has negligible effect on the electronic and field emission properties of the AlN nanotube. This process may increase the solubility of AlN nanotubes
    Full-text · Article · May 2013 · Comptes Rendus Chimie
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    ABSTRACT: We have investigated the adsorption of hydrogen fluoride (HF) on the AlN nanotube surface using density functional theory in terms of energetic, structural and electronic properties. By overcoming energy barriers of 27.90–52.30 kcal/mol, HF molecule is dissociated into H and F species on the tube surface and its molecular structure is not preserved after the adsorption process. Dissociation energies have been calculated to be -52.57 and -70.10 kcal/mol. The process has negligible effect on the electronic and field emission properties of the AlN nanotube. This process may increase the solubility of AlN nanotubes.
    No preview · Article · May 2013 · Comptes Rendus Chimie
  • Ali Ahmadi Peyghan · Mohammad T. Baei · Zargham Bagheri

    No preview · Article · Mar 2013 · Chinese journal of chemical physics
  • Ali Ahmadi Peyghan · Zargham Bagheri
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    ABSTRACT: By using density functional theory, the electronic response of a BC3 nanotube (BC3NT) to CS2 molecules was investigated. It was found that: (1) the CS2 adsorption on the tube is site-selective and it prefers to be adsorbed on a hexagonal ring of the tube which has six carbon atoms, liberating energy of about 34.36 kcal/mol; (2) the HOMO–LUMO energy gap (Eg) of the tube is significantly decreased from 2.37 to 1.70 eV upon the CS2 adsorption; (3) the Eg of the tube is more decreased by increasing the number of the adsorbed CS2 molecules; (4) the BC3NT may transform the presence of CS2 molecule into an electrical signal, and therefore it may be potentially used in CS2 sensors. Also, the response of the tube may be dependent on the concentration of the CS2 molecules.
    No preview · Article · Mar 2013 · Computational and Theoretical Chemistry
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    Mohammad Taghi Baei · Ali Ahmadi Peyghan · Zargham Bagheri

    Full-text · Article · Mar 2013 · Comptes Rendus Chimie
  • Mohammad T Baei · Ali Ahmadi Peyghan · Zargham Bagheri
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    ABSTRACT: Adsorption of NH 3 molecule on a carbon nanocone (CNC) was investigated using density functional theory in terms of energetic, structural, and electronic properties. It is mainly demonstrated that (i) the NH 3 molecule preferentially tends to attach to the apex of the CNC through its N atom, releasing energy of 54.28 kcal/mol,(ii) the CNC may be a promising candidate in gas sensor devices in order to detect the NH 3 molecule, and (iii) the field electron emission current may be enhanced from CNC surface upon the adsorption ...
    No preview · Article · Feb 2013 · Structural Chemistry