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Mirzaei M.,Islamic Azad University at Shahr Rey
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2010

NMR parameters consisting of isotropic and anisotropic chemical shielding parameters have been calculated based on density functional theory (DFT) to investigate the properties of the electronic structures of the silicon-carbon (SiC) doped boron nitride nanotubes (BNNTs). The structures have been allowed to relax by performing all atomic optimization. Afterwards, the chemical shielding (CS) parameters have been calculated for the B-11, C-13, N-15, and Si-29 atoms in the pristine and the SiC-doped models of the (4,4) armchair and (6,0) zigzag BNNTs. The results indicated that the doping of the B and N atoms by the C and Si atoms, respectively, has more significant influence on the calculated NMR parameters than the doping of the B and N atoms by the Si and C atoms, respectively. In comparison to the pristine model, the band gaps detect more changes in the former model of the doping process. © 2010 Elsevier B.V. All rights reserved. Source


Mirzaei M.,Islamic Azad University at South Tehran | Miirzaei M.,Islamic Azad University at Shahr Rey
Solid State Communications | Year: 2010

We have performed density functional theory (DFT) calculations to investigate the properties of the electronic structure of the oxygen (O) terminated zigzag boron nitride nanotubes (BNNTs). To this end, the atoms of the tips of the representative (6, 0) BNNT are doped by the O atoms. Electric field gradient (EFG) tensors have been calculated in different models of the investigated BNNT and converted to quadrupole coupling constants (Χ) for B-11, N-14 and O-17 atoms. Our results indicated that the influence of O-termination on the properties of the electronic structure of the (6, 0) BNNT could be detected by the values of Χ parameters. These values revealed that the strength of N-O bonds could be weaker than B-O ones. © 2010 Elsevier Ltd. All rights reserved. Source


Mirzaei M.,Islamic Azad University at Shahr Rey
Monatshefte fur Chemie | Year: 2010

Density-functional theory calculations have been performed to investigate the properties of the electronic structures of silicon-carbon-doped boron nitride nanotubes (BNNTs). The geometries of zigzag and armchair BNNTs were initially optimized and the quadrupole coupling constants subsequently calculated. The results indicate that doping of B and N atoms by C and Si atoms has more influence on the electronic structure of the BNNTs than does doping of B and N atoms by Si and C atoms. The changes of the electronic sites of the N atoms are also more significant than those of the B atoms. © Springer-Verlag 2010. Source


Mirzaei M.,Islamic Azad University at Shahr Rey
Zeitschrift fur Naturforschung - Section A Journal of Physical Sciences | Year: 2010

Structural properties of two representative (4,4) armchair and (6,0) zigzag boron phosphide nanotubes (BP-NTss) are studied by density functional theory (DFT) calculations. To this aim, both structures and also the equivalent layer-like structures are individually optimized; afterwards, the boron-11 and phosphorous-31 chemical shielding (CS) tensors are calculated in the optimized structures. The calculated energies indicate that tubular structures are stabilized and the CS tensors are divided into some layers based on equality of electronic properties in the structures. All computations are performed by Gaussian 98 program package. © 2010 Verlag der Zeitschrift für Naturforschung, Tübingen. Source


Mirzaei M.,Islamic Azad University at Shahr Rey | Nouri A.,Islamic Azad University
Journal of Molecular Structure: THEOCHEM | Year: 2010

We have investigated the properties of the electronic structure of the aluminum doped (Al-doped) boron nitride nanotubes (BNNTs) by density functional theory (DFT) calculations. The structures are allowed to relax by performing all atomic optimization. Afterwards, the chemical shielding (CS) tensors are calculated for B-11, N-15, and Al-27 nuclei in the Al-doped forms and also pristine models of the (4,4) armchair and (6,0) zigzag BNNTs. The results indicated that the doping of B atom by Al atom, the properties of the electronic structure were less influenced regarding to the pristine model than the case of doping of N atom by Al atom. Furthermore, doping of N atom by Al atom yields the equivalent calculated values of the band gaps for the Al-doped forms of the armchair and zigzag models of BNNTs. © 2009 Elsevier B.V. All rights reserved. Source

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