Yazar "Tomak, M" seçeneğine göre listele

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    Electronic properties of a large quantum dot at a finite temperature
    (ELSEVIER SCIENCE BV, 2005) Gulveren, B; Atav, U; Tomak, M
    The physical properties of a two-dimensional parabolic quantum dot composed of large number of interacting electrons are numerically determined by the Thomas Fermi (TF) method at a finite temperature. Analytical solutions are given for zero temperature for comparative purposes. The exact solution of the TF equation is obtained for the non-interacting system at finite temperatures. The effect of the number of particles and temperature on the properties are investigated both for interacting and non-interacting cases. The results indicate that the effect of e e interaction on the density profile shows different temperature dependencies above and below a certain temperature T-c. (c) 2005 Elsevier B.V. All rights reserved.
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    Electronic structure of a many-electron spherical quantum dot with an impurity
    (AMER PHYSICAL SOC, 2005) Sahin, M; Tomak, M
    We investigate the electronic structure of a many-electron spherical quantum dot with and without hydrogenic impurity. The number of electrons is taken as N=18. The density functional theory is used within local density approximation. Total energy, chemical potential, addition energy spectra, and the shell structure are determined and the results obtained are compared for cases with and without impurity. It is observed that the capacitive energy with the impurity increases in the 1s shell with respect to the case without the impurity.
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    Nonlinear optical rectification in asymmetrical semiparabolic quantum wells
    (PERGAMON-ELSEVIER SCIENCE LTD, 2005) Karabulut, I; Safak, H; Tomak, M
    The optical rectification in a semiparabolic quantum well is theoretically investigated. The electronic states in a semiparabolic quantum well are calculated exactly, within the envelope function and the displaced harmonic oscillator approach. The nonlinearity resulting from the asymmetry of the confining potential is studied in the lowest order. The numerical results for the typical AlxGa1-xAs/GaAs material show that the large optical rectification coefficient decreases with increasing confining potential frequency of the semiparabolic quantum well. Moreover, the optical rectification coefficient also depends sensitively on the relaxation rate of semiparabolic quantum well system. (C) 2005 Elsevier Ltd. All rights reserved.
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    A parabolic quantum dot with N electrons and an impurity
    (ELSEVIER SCIENCE BV, 2005) Gulveren, B; Atav, U; Sahin, M; Tomak, M
    Ground-state properties of a two-dimensional quantum dot composed of N electrons and an impurity are investigated by the Thomas-Fermi (TF) method at T = 0. The changes induced by the impurity in electron density, chemical potential and total energy are calculated. Calculations are also performed for different number of particles and strength of confinement. The results indicate that Thomas-Fermi approximation is applicable even when the system contains only a few particles. (c) 2005 Elsevier B.V. All rights reserved.
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    Quantum genetic algorithm method in self-consistent electronic structure calculations of a quantum dot with many electrons
    (WORLD SCIENTIFIC PUBL CO PTE LTD, 2005) Sahin, M; Atav, U; Tomak, M
    In this study, we have calculated energy levels of an N-electron quantum dot. For this purpose, we have used two different techniques, matrix diagonalization and quantum genetic algorithm, to obtain simultaneous solutions of the coupled Schrodinger and Poisson equation in the Hartree approximation. We have determined single particle energy levels, total energy, chemical potential and capacitive energy. We have also compared the results, demonstrated the applicability of QGA to many-electron quantum systems and evaluated its effectiveness.
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    The self-consistent calculation of a spherical quantum dot: A quantum genetic algorithm study
    (ELSEVIER SCIENCE BV, 2005) Sahin, M; Tomak, M
    In this study, we have calculated the subband energy level, potential profile, and the corresponding wavefunction and chemical potential for different temperatures and donor concentrations in a spherical quantum dot self-consistently. We have also investigated the effect of exchange-correlation potential on the energy levels. In addition, we have checked the applicability of quantum genetic algorithm to a realistic self-consistent quantum dot problem. In all computations, the penetration of wavefunction to the barrier region is taken into account. (c) 2005 Elsevier B.V. All rights reserved.