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  • 1.
    Baev, Alexander
    et al.
    Institute for lasers, Photonics and Biophotonics SUNY at Buffalo, USA.
    Henriksson, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Computational Physics .
    Norman, Patrick
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Computational Physics .
    Ågren, Hans
    KTH, Stockholm.
    A quantum mechanical - Electrodynamical approach to nonlinear properties: Application to optical power limiting with platinum-organic compounds2007In: Journal of nonlinear optical physics and materials, ISSN 0218-8635, Vol. 16, no 2, p. 157-169Article in journal (Refereed)
    Abstract [en]

    Light propagation in a medium is sensitively dependent on the shape and intensity of the optical pulse as well as on the electronic and vibrational structure of the basic molecular units. We review in this paper the results of systematic studies of this problem for isotropic media. Our theoretical approach - the quantum mechanical-electrodynamical (QMED) approach - is based on a quantum mechanical account of the many-level electron-nuclear medium coupled to a numerical solution of the density matrix and Maxwell's equations. This allows us to accommodate a variety of nonlinear effects which accomplish the propagation of strong light pulses. Particular attention is paid to the understanding of the role of coherent and sequential excitations of electron-nuclear degrees of freedom. The QMED combination of quantum chemistry with classical pulse propagation enables us to estimate the optical transmission from cross sections of multi-photon absorption processes and from considerations of propagation effects, saturation and pulse effects. Results of the theory suggest that in the nonlinear regime, it is often necessary to simultaneously account for coherent one-step and incoherent step-wise multi-photon absorption, as well as for off-resonant excitations even when resonance conditions prevail. The dynamic theory of nonlinear propagation of a few interacting intense light pulses is highlighted here in a study of the optical power limiting with platinum-organic molecular compounds. © World Scientific Publishing Company.

  • 2.
    Baev, Alexander
    et al.
    Institute for Lasers, Photonics and Biophotonics, SUNY at Buffalo, Buffalo, New York .
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Henriksson, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Ågren, Hans
    Theoretical Chemistry, Royal Institute of Technology, Stockholm.
    Theoretical Simulations of Clamping Levels in Optical Power Limiting2006In: Journal of Physical Chemistry B, ISSN 1520-5215, Vol. 110, no 42, p. 20912-20916Article in journal (Refereed)
    Abstract [en]

    Multiphysics modeling, combining quantum mechanical and classical wave mechanical theories, of clamping levels has been performed for a platinum(II) organic compound in a sol−gel glass matrix. A clamping level of 2.5 μJ is found for a pulse duration of 10 ns. The excited-state absorption in the triplet manifold is shown to be crucial for clamping to occur.

  • 3.
    Bast, Radovan
    et al.
    CNRS.
    Saue, Trond
    CNRS.
    Henriksson, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Norman , Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Role of noncollinear magnetization for the first-order electric-dipole hyperpolarizability at the four-component Kohn-Sham density functional theory level2009In: JOURNAL OF CHEMICAL PHYSICS, ISSN 0021-9606 , Vol. 130, no 2, p. 024109-Article in journal (Refereed)
    Abstract [en]

    The quadratic response function has been derived and implemented at the adiabatic four-component Kohn-Sham density functional theory level with inclusion of noncollinear spin magnetization and gradient corrections in the exchange-correlation functional-a work that is an extension of our previous report where magnetization dependencies in the exchange-correlation functional were ignored [J. Henriksson, T. Saue, and P. Norman, J. Chem. Phys. 128, 024105 (2008)]. The electric-field induced second-harmonic generation experiments on CF3Cl and CF3Br are addressed by a determination of (beta) over bar (-2 omega;omega,omega) for a wavelength of 694.3 nm, and the same property is also determined for CF3I. The relativistic effects on the static hyperpolarizability for the series of molecules amount to 1%, 5%, and 9%, respectively. At the experimental wavelength, the contributions to beta due to the magnetization dependence in the exchange-correlation functional are negligible for CF3Cl and CF3Br and small for CF3I. The noticeable effect of magnetization in the latter case is attributed to a near two-photon resonance with the excited state 1 E-3 (nonrelativistic notation). It is emphasized, however, that the effect of magnetization on beta for CF3I is negligible both in comparison to the total relativistic correction as well as to the effects of electron correlation. It is concluded that, in calculations of hyperpolarizabilities under nonresonant conditions, the magnetization dependence in the exchange-correlation functional may be ignored.

  • 4.
    Henriksson, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Light Control using Organometallic Chromophores2006Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The interaction between light and organometallic chromophores has been investigated theoretically in a strive for fast optical filters. The main emphasis is on two-photon absorption and excited state absorption as illustrated in the Jablonski diagram. We stress the need for relativistic calculations and have developed methods to address this issue. Furthermore, we present how quantum chemical calculations can be combined with Maxwell's equations in order to simulate propagation of laser pulses through a materials doped with chromophores with high two-photon absorption cross sections. Finally, we also discuss how fast agile filters using spin-transition materials can be modeled in order to accomplish theoretical material design.

  • 5.
    Henriksson, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Molecular Quadratic Response Properties with Inclusion of Relativity2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis concerns quadratic response properties and their application to properties in Jablonski diagrams such as resonant two-photon absorption and excited state absorption. Our main interest lies in optical power limiting applications, and in this context, molecules containing heavy metal atoms prove superior. Therefore, we are interested in how relativity affects these properties, and in order to assess this, a four-component relativistic framework is adopted.

    To properly address the molecular properties of interest, both relativistic effects and electron correlation need to be accounted for. These two properties are not additive, and, therefore, correlation needs to be incorporated into the four-component framework. We present the implementation of quadratic response properties at the four-component density functional level of theory. For second-harmonic generation, we have, with numerical examples, demonstrated that correlation and relativity are indeed not additive and that the inclusion of noncollinear magnetization is of little importance. We report that both electron correlation as well as relativity strongly affect results for second-harmonic generation. For example, relativity alone reduces the µβ-response signal by 62% and 75% for meta- and ortho-bromobenzene, respectively, and enhances the same response by 17% and 21% for meta- and ortho-iodobenzene, respectively.

    In the four-component framework, we present the implementations of single and double residues of the quadratic response function, which allows for the evaluation of resonant two-photon absorption cross sections and excited state properties. Using these tools, we discuss different levels of approximation to the relativistic Hamiltonian and we demonstrate that for two-photon absorption, a proper treatment of relativistic effects qualitatively alters the spectrum. For example, already for an element as light as neon, significant differences are seen between the relativistic and nonrelativistic spectra as triplet transitions acquire substantial absorption cross sections in the former case.

    Finally, quantum mechanics in conjunction with electrodynamics is applied to determine clamping levels in macroscopic samples. The microscopic properties of the optically active chromophores are determined by response theory, and then, electrodynamics is used to describe the interactions between the chromophores and incident laser pulses. Using this approach a series of molecules have been investigated and their performances have been compared and ranked in order to find novel materials for optical power limiting applications.

  • 6.
    Henriksson, Johan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Ekström, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    On the evaluation of quadratic response functions at the four-component Hartree-Fock level: Nonlinear polarization and two-photon absorption in bromo- and iodobenzen2006In: The Journal of Chemical Physics, ISSN 0021-9606, Vol. 124, no 21, p. 214311-Article in journal (Refereed)
    Abstract [en]

    The nonlinear polarization and two-photon absorption parameters have been determined for dibromo- and di-iodobenzene in their meta- and ortho-conformations and with relativistic effects accounted for to a varying degree. By exclusion of small component integrals in the calculations of the first-order hyperpolarizability, results within 1% of fully relativistic four-component Hartree-Fock values are obtained at a cost of 8.7 times the corresponding nonrelativistic calculations. It is shown that the nonlinear absorption in bromobenzene (and even more so in iodobenzene) is broad banded due to spin-orbit interactions among the excited states, and nonrelativistic and scalar relativistic calculations are not to be used in this case.

  • 7.
    Henriksson, Johan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Jensen, Hans Jørgen Aa.
    Department of Chemistry, University of Southern Denmark, Odense M, Denmark.
    Two-photon absorption in the relativistic four-component Hartree-Fock approximation2005In: The Journal of Chemical Physics, ISSN 0021-9606, Vol. 122, no 11, p. 114106-Article in journal (Refereed)
    Abstract [en]

    A first implementation of the single residue of the quadratic response function in the four-component Hartree–Fock approximation is presented. The implementation is based on a Kramers paired molecular orbital basis and takes full advantage of time and spatial symmetry reductions in a quaternion formulation—in analogy with the previous work on the quadratic response function [J. Chem. Phys. 121, 6145 (2004)]. Sample calculations are given in terms of the monochromatic and coherent two-photon absorption cross sections in the noble gases. The relativistic two-photon selection rule J={0,±2} allows for nonrelativistically spin-forbidden transitions, and, even in neon, strong two-photon absorption is shown to occur for the X  1S02  3P2 transition. It is argued that relevant comparisons between nonrelativistic and relativistic calculations must be performed at the level of integrated absorption cross sections.

  • 8.
    Henriksson, Johan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Nyrell, Susanna
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Theoretical design of optical switches using the spin transition phenomenon2006In: Computing Letters, ISSN 1574-0404, Vol. 2, no 4, p. 237-249Article in journal (Refereed)
    Abstract [en]

    The spin characteristics of octahedrically coordinated Fe(II) compounds are determined from first-principles quantum chemical calculations. Four novel Fe(II) spin transition materials are suggested for use in optical switching applications.

  • 9.
    Henriksson, Johan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Saue, Trond
    CNRS et Université Louis Pasteur.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Quadratic response functions in the relativistic four-component Kohn-Sham approximation2008In: The Journal of Chemical Physics, ISSN 0021-9606, Vol. 128, no 2, p. 024105-Article in journal (Refereed)
    Abstract [en]

    A formulation and implementation of the quadratic response function in the adiabatic four-component Kohn-Sham approximation is presented. The noninteracting reference state is time-reversal symmetric and formed from Kramers pair spinors, and the energy density is gradient corrected. Example calculations are presented for the optical properties of disubstituted halobenzenes in their meta and ortho conformations. It is demonstrated that correlation and relativistic effects are not additive, and it is shown that relativity alone reduces the µ-response signal by 62% and 75% for meta- and ortho-bromobenzene, respectively, and enhances the same response by 17% and 21% for meta- and ortho-iodobenzene, respectively. Of the employed functionals, CAM-B3LYP shows the best performance and gives hyperpolarizabilities distinctly different from B3LYP

  • 10.
    Tellgren, Erik
    et al.
    Department of Chemistry, University of Oslo, Oslo, Norway.
    Henriksson, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    First order excited state properties in the four-component Hartree-Fock approximation; the excited state electric dipole moments in CsAg and CsAu2007In: The Journal of Chemical Physics, ISSN 0021-9606, Vol. 126, no 6, p. 064313-Article in journal (Refereed)
    Abstract [en]

    An implementation of the second-order residue of the quadratic response function is presented in the four-component Hartree-Fock approximation, and the calculation of first-order properties of electronically excited states can thereby be achieved. Results are presented for the excited state electric dipole moments of the valence excited states in CsAg and CsAu. For CsAg, and even more so for CsAu, nonscalar relativistic effects on this property may be substantial, e.g., at the four-component level of theory, the excited-to-ground state dipole moment difference µ ranges from 1.994  to  4.110  a.u. for the six components of the 1  3 state in CsAg, whereas, at the scalar relativistic level of theory, the common value of µ is 2.494  a.u.

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