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On the evaluation of quadratic response functions at the four-component Hartree-Fock level: Nonlinear polarization and two-photon absorption in bromo- and iodobenzen
Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
2006 (English)In: The Journal of Chemical Physics, ISSN 0021-9606, Vol. 124, no 21, 214311- p.Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
2006. Vol. 124, no 21, 214311- p.
Keyword [en]
organic compounds, HF calculations, two-photon processes, relativistic corrections, polarisability, spin-orbit interactions, excited states
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:liu:diva-13999DOI: 10.1063/1.2204604OAI: oai:DiVA.org:liu-13999DiVA: diva2:22429
Available from: 2006-10-05 Created: 2006-10-05 Last updated: 2009-05-18
In thesis
1. Time-dependent molecular properties in the optical and x-ray regions
Open this publication in new window or tab >>Time-dependent molecular properties in the optical and x-ray regions
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Time-dependent molecular properties are important for the experimental characterization of molecular materials. We show how these properties can be calculated, for optical and x-ray frequencies, using novel quantum chemical methods. For xray absorption there are important relativistic effects appearing, due to the high velocity electrons near the atomic nuclei. These effects are treated rigorously within the four-component static exchange approximation. We also show how electron correlation can be taken into account in the calculation of x-ray absorption spectra, in time-dependent density functional theory based on the complex polarization propagator approach. The methods developed have been applied to systems of experimental interest|molecules in the gas phase and adsorbed on metal surfaces. The effects of molecular vibrations have been take into account both within and beyond the harmonic approximation.

Place, publisher, year, edition, pages
Institutionen för fysik, kemi och biologi, 2007
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1131
Keyword
Quantum chemistry, molecular physics, x-ray spectroscopy, relativity
National Category
Other Physics Topics
Identifiers
urn:nbn:se:liu:diva-10125 (URN)978-91-85895-88-5 (ISBN)
Public defence
2007-10-23, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2007-10-30 Created: 2007-10-30 Last updated: 2009-04-26
2. Molecular Quadratic Response Properties with Inclusion of Relativity
Open this publication in new window or tab >>Molecular Quadratic Response Properties with Inclusion of Relativity
2008 (English)Doctoral 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.

Place, publisher, year, edition, pages
Institutionen för fysik, kemi och biologi, 2008. 36 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1167
Keyword
relativistic quantum chemistry, molecular physics, clamping levels, four-component Hartree-Fock theory, Kohn-Sham density functional theory, response theory, nonlinear optics, second-harmonic generation, two-photon absorption, excited state properties, optical power limiting
National Category
Other Physics Topics
Identifiers
urn:nbn:se:liu:diva-11035 (URN)978-91-7393-957-7 (ISBN)
Public defence
2008-04-11, Planck, Hus E, Campus Valla, Linköping University, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2008-03-05 Created: 2008-03-05 Last updated: 2009-04-29
3. Light Control using Organometallic Chromophores
Open this publication in new window or tab >>Light Control using Organometallic Chromophores
2006 (English)Licentiate 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.

Place, publisher, year, edition, pages
Institutionen för fysik, kemi och biologi, 2006. 108 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1274
Keyword
organometallic chromophores, two-photon absorption, excited state absorption, excited state dipole moment, four-component formalism, clamping levels, spin-transition
National Category
Other Physics Topics
Identifiers
urn:nbn:se:liu:diva-17232 (URN)91-85643-77-7 (ISBN)
Presentation
(English)
Opponent
Supervisors
Note

Report code: LIU-TEK-LIC-2006:55. On the day of the defence date the status on article III was Manuscript, article IV was Accepted and article V was Submitted.

Available from: 2009-03-12 Created: 2009-03-12 Last updated: 2013-10-24Bibliographically approved

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Henriksson, JohanEkström, UlfNorman, Patrick

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