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    Comparison between stability, electronic, and structural properties of cagelike and spherical nanodiamond clusters

    , Article Physical Review B - Condensed Matter and Materials Physics ; Volume 76, Issue 3 , 2007 ; 10980121 (ISSN) Heidari Saani, M ; Kargarian, M ; Ranjbar, A ; Sharif University of Technology
    2007
    Abstract
    Ab initio density functional theory calculations were used to investigate cohesive, electronic, and structural properties of cagelike and spherical hydrogen terminated nanoparticles of diamond. Unlike cagelike nanodiamond particles, the variation of calculated energies of spherical ones is not monotonic. The variation range of the calculated energies and bond lengths of cagelike nanoparticles is much tighter than the variation range of spherical ones. In contrast to spherical nanodiamond particles, the C-C bond lengths of all cagelike nanoclusters are very similar to the bond length of bulk diamond. The comparison of stability, electronic highest occupied molecular orbital-lowest unoccupied... 

    Oscillator strength calculations in color centers of diamond and the role of spin

    , Article European Physical Journal B ; Volume 39, Issue 4 , 2004 , Pages 441-446 ; 14346028 (ISSN) Heidari Saani, M ; Vesaghi, M. A ; Esfarjani, K ; Sharif University of Technology
    2004
    Abstract
    A generalized Hubbard model based on a molecular approach is used to calculate many electron wavefunctions of diamond vacancies. We have calculated the oscillator strength of the dipole transition rates from the ground states of the neutral and negatively charged vacancies. The ratio of the oscillator strengths is in very good quantitative agreement with the reported optical spectroscopic data. Electronic configurations in the ground and dipole allowed excited states are presented. With the proposed picture, the much larger oscillator strength of the negatively charged vacancy with respect to other experimentally investigated color centers N-V, H3, X3 and H4 is explained  

    Generalized Hubbard model for many-electron states of the diamond vacancies: A non-CI approach

    , Article Physica Status Solidi (B) Basic Research ; Volume 243, Issue 6 , 2006 , Pages 1269-1275 ; 03701972 (ISSN) Heidari Saani, M ; Vesaghi, M. A ; Esfarjani, K ; Shafiekhani, A ; Sharif University of Technology
    2006
    Abstract
    Many-electron calculations based on a generalized Hubbard Hamiltonian for electronic states of the diamond vacancies are reported. The model does not use the configuration interaction (CI) method and proper tetrahedral symmetry and spin properties of the defect are included in the Hamiltonian. Atomic orbital bases are introduced for the Hamiltonian calculation. Excited states of both neutral and negatively charged vacancies in diamond are calculated. The calculated values for the experimentally observed first dipole transition energies of the vacancies in diamond, GR1 and ND1 bands, are in good agreement with experiment. To obtain these results, we used a semi-empirical Hamiltonian... 

    Metal-nonmetal transition in the copper-carbon nanocomposite films

    , Article Physica B: Condensed Matter ; Volume 405, Issue 18 , Jan , 2010 , Pages 3949-3951 ; 09214526 (ISSN) Ghodselahi, T ; Vesaghi, M. A ; Shafiekhani, A ; Ahmadi, M ; Panahandeh, M ; Heidari Saani, M ; Sharif University of Technology
    2010
    Abstract
    We prepared Cu nanoparticles in a-C:H thin films by co-deposition of RF-sputtering and RF-PECVD methods at room temperature. By increasing Cu content in these films a nonmetalmetal (NM) transition is observed. This transition is explainable by the power law of percolation theory. The critical metal content is obtained 56% and the critical exponent is obtained 1.6, which is larger than the exponent for 2 dimension systems and smaller than the one for 3 dimension systems. The electrical conductivity of dielectric samples was explained by tunneling. Activation tunneling energy that was obtained from temperature dependence of electrical resistivity correlates with near infrared absorption peak... 

    Many-electron states of nitrogen-vacancy centers in diamond and spin density calculations

    , Article Physical Review B - Condensed Matter and Materials Physics ; Volume 84, Issue 16 , 2011 ; 10980121 (ISSN) Ranjbar, A ; Babamoradi, M ; Heidari Saani, M ; Vesaghi, M. A ; Esfarjani, K ; Kawazoe, Y ; Sharif University of Technology
    2011
    Abstract
    Using a generalized Hubbard Hamiltonian, many-electron calculations of energy levels and corresponding wave functions of negatively charged and neutral nitrogen-vacancy centers in diamond were reported. The energies, orbital, and spin symmetries of the ground and excited states are in good quantitative agreement with available optical and electron paramagnetic resonance measurements. The many-electron wave functions were employed to predict the spin density on the N and C atoms in the ground and excited states. The present model explains the recent, experimentally observed definite nonzero spin density on N atom for the 4A2 excited state of the neutral charge state of NV (NV0) based on the... 

    Explanation of atomic displacement around lattice vacancies in diamond based on electron delocalization

    , Article European Physical Journal B ; Volume 65, Issue 2 , 2008 , Pages 219-223 ; 14346028 (ISSN) Heidari Saani, M ; Hashemi, H ; Ranjbar, A ; Vesaghi, M. A ; Shafiekhani, A ; Sharif University of Technology
    2008
    Abstract
    The relationship between unpaired electron delocalization and nearest-neighbor atomic relaxations in the vacancies of diamond has been determined in order to understand the microscopic reason behind the neighboring atomic relaxation. The Density Functional Theory (DFT) cluster method is applied to calculate the single-electron wavefunction of the vacancy in different charge states. Depending on the charge and spin state of the vacancies, at outward relaxations, 84-90% of the unpaired electron densities are localized on the first neighboring atoms. The calculated spin localizations on the first neighboring atoms in the ground state of the negatively charged vacancy and in the spin quintet... 

    Relationship between lattice relaxation and electron delocalization in diamond vacancies

    , Article Proceedings of the 23rd International Conference on Defects in Semiconductors, 24 July 2005 through 29 July 2005 ; Volume 376-377, Issue 1 , 2006 , Pages 324-326 ; 09214526 (ISSN) Heidari Saani, M ; Esfarjani, K ; Hashemi, H ; Vesaghi, M. A ; Basiri, A. R ; Sharif University of Technology
    2006
    Abstract
    Single electron wavefunction of a vacancy in diamond lattice has been calculated in different symmetric configurations of the nearest neighbor (NN) atoms. We used ab initio density functional theory (DFT) and unrestricted Hartree-Fock (UHF) cluster methods. The variation of electron or spin localization on NN atoms have been investigated with respect to the lattice relaxation in the ground state of the neutral and negatively charged vacancy. Calculated variations are not symmetric with respect to the sign of the lattice relaxation. We obtain about 90% localization for electronic charge and spin density for the neutral and negatively charged vacancy, respectively. This is in good agreement... 

    Facile synthesis of CuO@PbS core/shell nanowire arrays

    , Article Materials Letters ; Volume 193 , 2017 , Pages 259-262 ; 0167577X (ISSN) Farshidi, H ; Youzbashi, A. A ; Heidari Saani, M ; Rashidi, A ; Kazemzadeh, A ; Kiani, F ; Sharif University of Technology
    2017
    Abstract
    Nanowire arrays of copper oxide were first grown vertically using simple and cost effective thermal oxidation method on a copper foil. Subsequently, in order to deposit and grow PbS nanocyrstalline thin films on CuO NWs by utilizing the chemical bath deposition technique, these arrays were immersed as the substrate in the reaction solution consisting of Pb(NO3)2, (NH2)2CS and NaOH. The final products were characterized in detail by which the formation of uniform, unique arrays of CuO@PbS core–shell NWs was confirmed. Due to the nature of methods employed in synthesis of this hetero structure, the tuning of core and shell size and consequently properties of the novel structure is easily... 

    Lattice relaxation in many-electron states of the diamond vacancy

    , Article Physical Review B - Condensed Matter and Materials Physics ; Volume 71, Issue 3 , 2005 ; 10980121 (ISSN) Heidari Saani, M ; Vesaghi, M. A ; Esfarjani, K ; Ghods Elahi, T ; Sayari, M ; Hashemi, H ; Gorjizadeh, N ; Sharif University of Technology
    2005
    Abstract
    Symmetric lattice relaxation around a vacancy in diamond and its effect on many electron states of the defect have been investigated. A molecular approach is used to evaluate accurately electron-electron (e-e) interaction via a semiempirical formalism which is based on a generalized Hubbard Hamiltonian. Coupling of the defect molecule to surrounding bulk is also considered using an improved Stillinger-Weber potential for diamond. Strong dependence of the electronic energy levels to the relaxation size of the nearest neighbor (NN) atoms indicates that in order to obtain quantitative results the effect of lattice relaxation should be considered. Except for the high spin state of the defect 5A... 

    Spin Density and Entanglement Calculation for Many-Electron States of Nitrogen-Vacancy Centers in Diamond

    , M.Sc. Thesis Sharif University of Technology Babamoradi, Mohsen (Author) ; Vesaghi, Mohammad Ali (Supervisor) ; Heidari Saani, Mehdi (Supervisor)
    Abstract
    Nitrogen-Vacancy (NV) consists of a substitutional nitrogen located at a lattice site adjacent to a carbon vacancy. It has attracted much attention due to its application in solid state quantum information processing. Its long coherence time and ability to be used in ambient temperature made it a major candidate for quantum bit (Qbit). Due to its importance, a lot of theoretical studies for the NV’s properties based on the DFT and other single particle approaches have been done, while many-body approaches are not expanded so. For the first time, a generalized Hubbard Hamiltonian was used as a many-body approach to study NV defects. The obtained wavefunctions and states result to good... 

    CO gas sensor properties of Cu@CuO core-shell nanoparticles based on localized surface plasmon resonance

    , Article Journal of Physical Chemistry C ; Volume 115, Issue 45 , 2011 , Pages 22126-22130 ; 19327447 (ISSN) Ghodselahi, T ; Zahrabi, H ; Saani, M. H ; Vesaghi, M. A ; Sharif University of Technology
    2011
    Abstract
    Hexagonal array of Cu@CuO core-shell nanoparticles (NPs) on the a-C:H thin film was prepared by codeposition of RF-sputtering and RF-PECVD. The trace of hexagonal NPs supperlattice was recognized by AFM image and XRD result. On the basis of localized surface plasmon resonance (LSPR) of core-shell NPs, the prepared array detected a low flow rate of CO gas at room temperature. XPS results indicate that the surface of Cu@CuO core-shell NPs have no chemical reaction with CO molecule. The physical absorption of CO molecule on the surface of Cu@CuO core-shell NPs increases the LSPR absorbance and causes a red shift in LSPR wavelength. These experimental results are in agreement with Mie theory... 

    Details of a theoretical model for electronic structure of the diamond vacancies

    , Article Proceedings of the 9th International Conference on New Diamond, Tokyo, 26 March 2004 through 29 March 2004 ; Volume 13, Issue 11-12 , 2004 , Pages 2125-2130 ; 09259635 (ISSN) Saani, M. H ; Vesaghi, M. A ; Esfarjani, K ; Shafiekhani, A ; Sharif University of Technology
    2004
    Abstract
    A new model to calculate electronic states of the diamond vacancies has been developed using many body techniques. This model is based on physical assumptions of previous molecular models but does not use configuration interaction. Present model allows an accurate and unified treatment of electronic levels and related eigen functions for diamond vacancies, in addition to transition energies of the first dipole-allowed transitions in the neutral (V0) and negatively charged (V-) vacancies, GR1 and ND1 band. For the first time, we calculated their optical transition intensities. For obtaining these results, we solved a generalized form of the Hubbard Hamiltonian, which consists of all... 

    Effect of lattice relaxation on spin density of nitrogen-vacancy centers in diamond and oscillator strength calculations

    , Article European Physical Journal B ; Volume 84, Issue 1 , 2011 , Pages 1-9 ; 14346028 (ISSN) Babamoradi, M ; Heidari Saani, M ; Ranjbar, A ; Vesaghi, M. A ; Kawazoe, Y ; Sharif University of Technology
    2011
    Abstract
    Using a generalized Hubbard Hamiltonian, many-electron wavefunctions of negatively charged (NV -) and neutral nitrogen-vacancy (NV 0) centers in diamond were calculated. We report the effect of symmetric relaxation of surrounding atoms on the spin density, calculated from the many electron wavefunctions in the ground and excited states. We evaluated the error, that, arises in estimation of spin density when lattice relaxation effect is neglected in Electron Paramagnetic Resonance experiment and showed that the ground state spin density distribution is accessible in outward relaxations. The computed oscillator strengths give a higher efficiency for the 1.945 eV photoluminescence (PL) line of... 

    Correlation between entanglement and spin density in nitrogen-vacancy center of diamond

    , Article European Physical Journal D ; Volume 65, Issue 3 , 2011 , Pages 597-603 ; 14346060 (ISSN) Babamoradi, M ; Heidari Saani, M ; Ranjbar, A ; Vesaghi, M. A ; Kawazoe, Y ; Sharif University of Technology
    2011
    Abstract
    Many-body wavefunctions were utilized to calculate von Neumann's entropy as an entanglement measurement for neutral and negatively charged nitrogen vacancy (NV) centers in diamond. A generalized Hubbard Hamiltonian which considers e-e interaction terms completely was used to calculate many-electron wavefunctions of the ground and excited states. Correlation between entanglement and spin density distributed on neighboring atoms of NV is presented. The behavior of spin density and entanglement under relaxations of neighboring atoms is the same for all investigated ground and excited states. The results suggest that the spin density may be used to quantify the entanglemnt and vice versa  

    Reliability evaluation in power distribution system planning studies

    , Article 2016 International Conference on Probabilistic Methods Applied to Power Systems, PMAPS 2016 - Proceedings, 16 October 2016 through 20 October 2016 ; 2016 ; 9781509019700 (ISBN) Heidari, S ; Fotuhi Firuzabad, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    Abstract
    In distribution system planning studies, reliability evaluation is performed during optimization procedure to calculate the interruption cost, DISCO's income and to check the viability of constraints related to reliability indices. In each iteration of the optimization algorithm a special plan is evaluated that is different from other plans. So the configuration and specification of the network which is one of the input information for reliability evaluation is changing continuously that makes difficulties for this evaluation. To solve these difficulties, this paper presents a systematic method for reliability evaluation in distribution planning studies. The proposed approach can be... 

    Probabilistic risk assessment of oil spill from offshore oil wells in Persian Gulf

    , Article Marine Pollution Bulletin ; Volume 136 , 2018 , Pages 291-299 ; 0025326X (ISSN) Amir Heidari, P ; Raie, M ; Sharif University of Technology
    2018
    Abstract
    Oil spills in the marine environment can have serious environmental, social and economic impacts. These impacts may be of transnational nature, and this makes the oil spill problem an international issue. Therefore, it is necessary to develop a common structured methodology for oil spill risk assessment. In this research, a general framework is presented for probabilistic risk assessment of oil spill from offshore oil wells. A case study is also performed in Persian Gulf to quantify the risk posed by 357 offshore wells to the near-shore receptors. First, thousands of hypothetical spill scenarios of different volumes are defined and simulated using a Lagrangian particle tracking model. Then,... 

    A new stochastic oil spill risk assessment model for Persian Gulf: Development, application and evaluation

    , Article Marine Pollution Bulletin ; Volume 145 , 2019 , Pages 357-369 ; 0025326X (ISSN) Amir Heidari, P ; Raie, M ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    Persian Gulf is a semi-enclosed highly saline reverse estuary that is exposed to the risk of oil spills in offshore oil and gas activities. In the early 2000s, a specific version of NOAA's Trajectory Analysis Planner (TAP II) was developed for Persian Gulf to assist regional organizations in preparing oil spill contingency plans. In this research, a new stochastic model is developed to cover the limitations of TAP II. The new model is based on an advanced trajectory model, which is now linked with high resolution spatiotemporal data of the wind and sea current. In a case study, the developed model is compared with TAP II, and evaluated by multiple tests designed for analysis of uncertainty,... 

    Integrated planning for distribution automation and network capacity expansion

    , Article IEEE Transactions on Smart Grid ; Volume 10, Issue 4 , 2019 , Pages 4279-4288 ; 19493053 (ISSN) Heidari, S ; Fotuhi Firuzabad, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    Due to the large amount of resources needed for implementing distribution automation systems (DASs), distribution companies (DISCOs) should develop long term plans for this project. Similarly, DISCOs have network capacity expansion (NCX) plans which specify the scheme of constructing the feeders and substations. Since considering DAS may lead to more efficient NCX plans, the planner should revise the NCX plan through the DAS planning. On the other hand, for DAS planning it is necessary to consider a NCX plan as a platform to determine the time and location for installation of automation equipment. Therefore the planner should simultaneously work on two plans, each of them affects the other.... 

    Integrated planning for distribution automation and network capacity expansion

    , Article IEEE Transactions on Smart Grid ; 12 July , 2018 , Page(s): 1 - 1 ; 19493053 (ISSN) Heidari, S ; Fotuhi Firuzabad, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    Due to the huge amount of resources needed for implementing distribution automation systems (DAS), distribution companies (DISCOs) should develop long term plans for this project. Similarly, DISCOs have network capacity expansion (NCX) plans which specify the scheme of constructing the feeders and substations. Since considering DAS may lead to more efficient NCX plans, the planner should revise the NCX plan through the DAS planning. On the other hand, for DAS planning it is necessary to consider a NCX plan as a platform to determine the time and location for installation of automation equipment. Therefore the planner should simultaneously work on two plans, each of them affects the other. To... 

    Response planning for accidental oil spills in persian gulf: a decision support system (DSS) based on consequence modeling

    , Article Marine Pollution Bulletin ; Volume 140 , 2019 , Pages 116-128 ; 0025326X (ISSN) Amir Heidari, P ; Raie, M ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    Different causes lead to accidental oil spills from fixed and mobile sources in the marine environment. Therefore, it is essential to have a systematic plan for mitigating oil spill consequences. In this research, a general DSS is proposed for passive and active response planning in Persian Gulf, before and after a spill. The DSS is based on NOAA's advanced oil spill model (GNOME), which is now linked with credible met-ocean datasets of CMEMS and ECMWF. The developed open-source tool converts the results of the Lagrangian oil spill model to quantitative parameters such as mean concentration and time of impact of oil. Using them, two new parameters, emergency response priority number (ERPN)...