Yazar "El Kouari, Y." seçeneğine göre listele

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    Ab-initio and DFT methodologies for computing hyperpolarizabilities and susceptibilities of highly conjugated organic compounds for nonlinear optical applications
    (ELSEVIER SCIENCE BV, 2016) Karakas, A.; Karakaya, M.; Ceylan, Y.; El Kouari, Y.; Taboukhat, S.; Boughaleb, Y.; Sofiani, Z.
    In this talk, after a short introduction on the methodologies used for computing dipole polarizability (alpha), second and third-order hyperpolarizability and susceptibility; the results of theoretical studies performed on density functional theory (DFT) and ab-initio quantum mechanical calculations of nonlinear optical (NLO) properties for a few selected organic compounds and polymers will be explained. The electric dipole moments (mu) and dispersion-free first hyperpolarizabilities (beta) for a family of azo-azulenes and a styrylquinolinium dye have been determined by DFT at B3LYP level. To reveal the frequency dependent NLO behavior, the dynamic a, second hyperpolarizabilities (gamma), second (chi((2))) and third-order (chi((3))) susceptibilites have been evaluated using time-dependent HartreeFock (TDHF) procedure. To provide an insight into the third-order NLO phenomena of a series of pyrrolo-tetrathiafulvalene-based molecules and pushpull azobenzene polymers, two-photon absorption (TPA) characterizations have been also investigated by means of TDHF. All computed results of the examined compounds are compared with their previous experimental findings and the measured data for similar structures in the literature. The one-photon absorption (OPA) characterizations of the title molecules have been theoretically obtained by configuration interaction (CI) method. The highest occupied molecular orbitals (HOMO), the lowest unoccupied molecular orbitals (LUMO) and the HOMO-LUMO band gaps have been revealed by DFT at B3LYP level for azo-azulenes, styrylquinolinium dye, push-pull azobenzene polymers and by parametrization method 6 (PM6) for pyrrolo-tetrathiafulvalene-based molecules. (C) 2016 Elsevier B.V. All rights reserved.
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    Comparison between Quantum Mechanical Computations of NLO Properties and Experimental Data in Selected Functionalized Azo-Dyes
    (IEEE, 2012) Sahraoui, B.; Karakas, A.; Hajjaji, A.; El Kouari, Y.; Migalska-Zalas, A.
    Nonlinear optical (NLO) materials have been extensively studied for many years. The search of new materials with NLO properties is an important research field. Significant interest still exists in the design and development of materials exhibiting large second and third-order NLO response because of the potential application in optoelectronics devices [1-2]. In this talk, comparison between quantum mechanical computations of NLO properties and experimental data in selected azo-dyes will be done. Particularly we will focus on correlation between macroscopic level and microscipic one. To reveal the microscopic second-order NLO properties of a family of azo-azulenes, the electric dipole moments (mu) and static first hyperpolarizabilities (beta) have been evaluated by using density functional theory (DFT) quantum mechanical calculations at B3LYP/6-311+G (d, p) level. The calculation results with non-zero values on first hyperpolarizabilities indicate that the title molecules might possess microscopic second-order NLO phenomena. The maximum one-photon absorption (OPA) wavelengths obtained by theoretical computations using the configuration interaction (CI) method are located in the visible region, supporting the pi -> pi* transitions. We have also calculated the dynamic second (chi((2))) and third-order chi((3)) susceptibilities using the time-dependent Hartree-Fock (TDHF) method.
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    Computational studies on linear, second and third-order nonlinear optical properties of novel styrylquinolinium dyes
    (ELSEVIER, 2016) Karakas, A.; Karakaya, M.; Taser, M.; Ceylan, Y.; Gozutok, A.; Arof, A. K.; El Kouari, Y.
    The electric dipole moments (mu), static dipole polarizabilities (alpha) and first hyperpolarizabilities (beta) of styrylquinolinium dyes, D8 and D21, have been computed by density functional theory (DFT). The one photon absorption (OPA) characterizations have been investigated using UV-vis spectroscopy and further interpreted using computational chemistry. The time-dependent Hartree-Fock (TDHF) method has been used to describe the dynamic dipole polarizabilities, dynamic second-order and also static and dynamic third-order nonlinear optical (NLO) properties. D8-D21 have rather high beta and second hyperpolarizabilities (gamma). The highest occupied molecular orbitals (HOMO), the lowest unoccupied molecular orbitals (LUMO) and the HOMO-LUMO band gaps for D8-D21 have been evaluated by DFT. (C) 2016 Elsevier B.V. All rights reserved.
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    One-photon Absorption Characterizations, Dipole Polarizabilities and Second Hyperpolarizabilities of Chlorophyll a and Crocin
    (SCIENDO, 2018) Karakas, A.; Ceylan, Y.; Karakaya, M.; Taser, M.; Terlemez, B. B.; Eren, N.; El Kouari, Y.
    The dispersion-free dipole polarizability (alpha) computations for chlorophyll a (1) and crocin (2) have been achieved by density functional theory (DFT) at B3LYP/ 6-31G(d) level. The measured one-photon absorption (OPA) wavelengths are quite consistence with the theoretically obtained values. Ab-initio quantum chemical calculations (time-dependent Hartree-Fock (TDHF)) have been implemented to reveal the static second hyperpolarizabilities (gamma) and dynamic dipole polarizabilities of the title molecules. The examined compounds display gamma with non-zero values, introducing their third-order nonlinear optical (NLO) phenomena. The first and second frontier molecular orbitals of the investigated molecules have been also derived from DFT.
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    Quantum chemical calculations and experimental studies of third-order nonlinear optical properties of conjugated TTF-quinones
    (ELSEVIER SCIENCE BV, 2013) Karakas, A.; Migalska-Zalas, A.; El Kouari, Y.; Gozutok, A.; Karakaya, M.; Touhtouh, S.
    To investigate microscopic third-order nonlinear optical (NLO) behaviour of two tetrathiafulvalene (TTF) derivatives, TTF-diquinone triad (1) and TTF-monoquinone dyad (2), we have computed both dispersion-free and also dispersion of dipole polarizabilities (alpha) and third-order hyperpolarizabilities (gamma) at 532 nm wavelength using time-dependent Hartree-Fock (TDHF) method. The one-photon absorption (OPA) characterizations of the title molecules have been theoretically obtained by means of configuration interaction (CI) method with all doubly occupied molecular orbitals. We have also calculated the dynamic third-order susceptibilities (chi((3))) using the TDHF method. Our theoretical results on the maximum OPA wavelengths, third-order susceptibilities and corresponding microscopic NLO responses are in good agreement with the previous experimental observations of the examined TTF-based molecules. The highest occupied molecular orbitals (HOMO), the lowest unoccupied molecular orbitals (LUMO) and the HOMO-LUMO band gaps for I and 2 have been evaluated by density functional theory (DFT) quantum mechanical calculations at B3LYP/6-31 G(d,p) level. (C) 2013 Elsevier B.V. All rights reserved.
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    Second and third-order nonlinear optical behavior of natural pigment: chlorophyll and crocin
    (SPRINGER HEIDELBERG, 2017) Karakas, A.; Karakaya, M.; Taser, M.; Ceylan, Y.; Arof, A. K.; El Kouari, Y.; Sahraoui, B.
    To provide an insight into the microscopic second and third-order nonlinear optical (NLO) behavior of chlorophyll a and crocin, we have computed the electric dipole moments (mu), dispersion-free first hyperpolarizabilities (beta), frequency-dependent first and second (gamma) hyperpolarizabilities at 1064 nm wavelength area using time-dependent Hartree-Fock (TDHF) method. According to ab-initio calculation results, the examined compounds exhibit first and second hyperpolarizabilities with non-zero values, implying second and third-order NLO phenomena.
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    Theoretical diagnostics of second and third-order hyperpolarizabilities of several acid derivatives
    (DE GRUYTER POLAND SP ZOO, 2019) Karakas, A.; Ceylan, Y.; Karakaya, M.; Taser, M.; Terlemez, B. B.; Eren, N.; El Kouari, Y.
    The density functional theory (DFT) at B3LYP/6-31G(d) level has been utilized to achieve the electric dipole moment (mu), static dipole polarizability (alpha) and first hyperpolarizability (beta) values for ferulic acid (1) and chenodeoxycholic acid (2). The time-dependent Hartree-Fock (TDHF) technique as a powerful quantum chemical method has been implemented to reveal the dynamic alpha, beta and third-order hyperpolarizabilities (gamma) of the examined compounds. Our computational conclusions have been compared with the results of similar materials in the literature. The first and second frontier molecular orbitals (MOs) and their band gaps have also been investigated by means of DFT.