Search for: coulomb-interactions
0.007 seconds

    Pressure dependence of effective Coulomb interaction parameters in BaFe2As2 by first-principle calculation

    , Article Physica C: Superconductivity and its Applications ; Volume 548 , 15 May , 2018 , Pages 61-64 ; 09214534 (ISSN) Aghajani, M ; Hadipour, H ; Akhavan, M ; Sharif University of Technology
    Elsevier B.V  2018
    Pressure dependence of the onsite Coulomb interactions of the BaFe2As2 has been studied by employing the constrained random phase approximation within first-principle calculations. Analyzing total and projected density of states, a pseudogap is found for dxy band at the energy roughly 0.25 eV higher than the Fermi level. Also, by applying pressure the spectral weight of the dxy orbital vanishes while other orbitals remain metallic. The different screening channels, as discussed in four different models, affect significantly on the Hubbard U while the Hund J remains almost unchanged. The average onsite bare and partially and fully screened Coulomb interactions increase with different rates... 

    From continuous to quantized charging phenomena in few nanocrystals MOS structures

    , Article 11th International Autumn Meeting on Gettering and Defect Engineering in Semiconductor Technlogy, GADEST 2005, Giens, 25 September 2005 through 30 September 2005 ; Volume 108-109 , 2005 , Pages 25-32 ; 10120394 (ISSN); 3908451132 (ISBN); 9783908451136 (ISBN) BenAssayag, G ; Shalchian, M ; Grisolia, J ; Bonafos, C ; Atarodi, S. M ; Claverie, A ; Sharif University of Technology
    Trans Tech Publications Ltd  2005
    In this paper, we present a study on the contribution of silicon nanocrystals to the electrical transport characteristics of large (100 μm × 100 μm) and small (100 nm × 100 nm) metaloxide-semiconductor (MOS) capacitors at room temperature. A layer of silicon nanocrystals is synthesized within the oxide of these capacitors by ultra-low energy ion implantation and annealing. Several features including negative differential resistance (NDR), sharp current peaks and random telegraph signal (RTS) are demonstrated in the current-voltage and current-time characteristics of these capacitors. These features have been associated to charge storage in silicon nanocrystals and to the resulting Coulomb... 

    An Investigation into Entanglement in Electrical Transport in a One-dimensional Model Using Transfer Matrix Method

    , M.Sc. Thesis Sharif University of Technology Safari, Maryam (Author) ; Rezakhani, Ali (Supervisor) ; Shokri, Ali Asghar (Co-Supervisor)
    This thesis analyzes the scattering of a propagating electron from a single bound electron .The study demonstrates how the scattering of the propagating electron from the bound electron causes entanglement between two electrons. The study then considers the impact of spin-dependent scattering in the presence of Hartree and exchange potentials. In the first step, only an exchange potential is studied. Transmission coefficients are calculated for spin-flip and non-spin-flip states by solving the Hamiltonian equation in different regions, applying the continuity boundary conditions for the wave function and its derivative in each region, and using the transfer matrix method. Transmission... 

    First-principle Study of Pressure Effects on the Structural and Magnetic Phase Transitions and the Electronic Structure of AeFe2As2(Ae=Ba,Sr,Ca) Compounds

    , Ph.D. Dissertation Sharif University of Technology Aghajani, Mahdieh (Author) ; Akhavan, Mohammad (Supervisor) ; Hadipour, Hanif (Co-Supervisor)
    The ternary 122-type AeFe2As2 (Ae=Ba,Sr,Ca) compounds are antiferromagnetic metals with the orthorhombic lattice structure at ambient pressure and low temperature. By applying mechanical pressure, structural, magnetic and superconducting transitions occur in these compounds. The isovalent doping of Ba with Sr and Ca elements induces chemical pressure and reduces the onset pressure of these transitions. The main purpose of this thesis is to investigate and compare the effects of mechanical and chemical pressures on the structural and magnetic phase transition in the 122 compounds. To achieve this purpose, we have done first-principle calculations for many properties such as the structural... 

    Mechanistic understanding of the interactions between nano-objects with different surface properties and α-synuclein

    , Article ACS Nano ; Volume 13, Issue 3 , 2019 , Pages 3243-3256 ; 19360851 (ISSN) Mohammad Beigi, H ; Hosseini, A ; Adeli, M ; Ejtehadi, M. R ; Christiansen, G ; Sahin, C ; Tu, Z ; Tavakol, M ; Dilmaghani Marand, A ; Nabipour, I ; Farzadfar, F ; Otzen, D. E ; Mahmoudi, M ; Hajipour, M. J ; Sharif University of Technology
    American Chemical Society  2019
    Aggregation of the natively unfolded protein α-synuclein (α-syn) is key to the development of Parkinson's disease (PD). Some nanoparticles (NPs) can inhibit this process and in turn be used for treatment of PD. Using simulation strategies, we show here that α-syn self-assembly is electrostatically driven. Dimerization by head-to-head monomer contact is triggered by dipole-dipole interactions and subsequently stabilized by van der Waals interactions and hydrogen bonds. Therefore, we hypothesized that charged nano-objects could interfere with this process and thus prevent α-syn fibrillation. In our simulations, positively and negatively charged graphene sheets or superparamagnetic iron oxide... 

    Electrostatic accumulation and determination of triclosan in ultrathin carbon nanoparticle composite film electrodes

    , Article Analytica Chimica Acta ; Volume 593, Issue 1 , 2007 , Pages 117-122 ; 00032670 (ISSN) Amiri, M ; Shahrokhian, S ; Psillakis, E ; Marken, F ; Sharif University of Technology
    A film composed of carbon nanoparticles and poly(diallyldimethylammonium chloride) or CNP-PDDAC is formed in a layer-by-layer deposition process at tin-doped indium oxide (ITO) substrates. Excess positive binding sites within this film in aqueous phosphate buffer at pH 9.5 are quantified by adsorption of iron(III)phthalocyanine tetrasulfonate and indigo carmine. Both anionic redox systems bind with Langmuirian characteristics (K ≈ 105 mol-1 dm3) and show electrochemical reactivity throughout the film at different thicknesses. Therefore, the electrical conductivity in CNP-PDDAC films is good and the positive binding sites are approximately 140 pmol cm-2 per layer. Structural instability of...