H Milani Moghaddam
Articles written in Pramana – Journal of Physics
Volume 69 Issue 4 October 2007 pp 661-668 Research Articles
S A Ketabi H Milani Moghaddam N Shahtamasebi
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 (
Volume 74 Issue 4 April 2010 pp 633-641 Research Articles
On the excited state wave functions of Dirac fermions in the random gauge potential
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.
Volume 76 Issue 6 June 2011 pp 965-972
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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