• H Milani Moghaddam

      Articles written in Pramana – Journal of Physics

    • Electron transport through SWNT/trans-PA/ SWNT structure (the role of solitons): A t-matrix technique

      S A Ketabi H Milani Moghaddam N Shahtamasebi

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      Using a tight-binding model and a transfer-matrix technique, we numerically investigate the effects of the coupling strength and the role of solitons on the electronic transmission through a system in which trans-polyacetylene (trans-PA) molecule is sandwiched between two semi-infinite single-walled carbon nanotubes (SWNT). We rely on Landauer formalism as the basis for studying the conductance properties of this system. Our calculations show that the solitons play an important role in the response of this system causing a large enhancement in the conductance. Also our results suggest that the conductance is sensitive to the CNT/molecule coupling strength.

    • On the excited state wave functions of Dirac fermions in the random gauge potential

      H Milani Moghaddam

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      In the last decade, it was shown that the Liouville field theory is an effective theory of Dirac fermions in the random gauge potential (FRGP). We show that the Dirac wave functions in FRGP can be written in terms of descendents of the Liouville vertex operator. In the quasiclassical approximation of the Liouville theory, our model predicts 22.2 that the localization length 𝜉 scales with the energy 𝐸 as $\xi \sim E^{−b^{2}(1+b^{2})^{2}}$, where 𝑏 is the strength of the disorder. The self-duality of the theory under the transformation $b \rightarrow 1/b$ is discussed. We also calculate the distribution functions of $t_{0} = |\psi_{0} (x)|^{2}$, (i.e. $p(t_{0}$); $\psi_{0}(x)$ is the ground state wave function), which behaves as the log-normal distribution function. It is also shown that in small $t_{0}$, $p(t_{0})$ behaves as a chi-square distribution.

    • The effect of C atom concentration on the electronic properties of boron carbonitride alloy nanotube in zig-zag form

      H Milani Moghaddam

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      Electronic properties of single-walled boron nitride nanotube in zig-zag form are numerically investigated by replacing B atoms with C atoms. Using a tight-binding Hamiltonian, the methods based on Green’s function theory, Landauer formalism and Dyson equation, the electronic density of states and electronic conductance in boron nitride nanotube and boron carbonitride nanotube are calculated. Our calculations indicate that in a boron nitride nanotube, the localized states associated with C impurities appear as the concentration of C atoms increases. The boron carbonitride nanotube thus behaves like a semiconductor. Also, by increasing the C atom concentration, the voltage in the first step on the $I–V$ characteristics decreases, whereas the corresponding current increases.

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