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Juniorprofessur Theoretische Chemie Instutut für Physikalische Chemie Christian-Albrechts-Universität zu Kiel Olshausenstr. 40 D-24098 Kiel Germany Phone: +49 (0)431 880 5821 Fax:: +49 (0)431 880 5810 Email: degorova@gmail.com Office: Max-Eyth-Str. 2, Raum 28 |
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TeachingTheoretical Chemistry/Theoretische Chemie, chem1004DMathematics for Chemists/Mathematik für Chemiker, chem0102 Theoretical Chemistry, Master chem1004DContents:* Formalismus der Quantenmechanik: Wellenfunktion, Operatoren, Schrödingergleichung, Erwartungswerte, Eigenwerte und Eigenfunktionen, Unschärferrelation, Ehrenfesttheorem * Exakt lösbare Probleme: freies Teilchen, Teilchen im Kasten, harmonscher Oszillator, H-Atom * Nährungsverfahren: Störungstheorie, Variationsprinzip * Mehrelektronensysteme: Eektronenspin, Pauli-Prinzip, He-Atom * enfachste zweiatomige Systeme: H2+, H2 * Quantenchemie: Hartree-Fock, CI, MP2, DFT * Quantendynamik: Born-Oppenheimer, Potenzialflächen (Basisentwicklung, Supperposition, Wellenpakete), Dichtenmatrix-Methoden, MCTDH Literature: * P.W. Atkins, Molecular Quantum Mechanics * I.N. Levine, Quantum Chemistry * A.S. Davydov, Quantum Mechanics (Quantenmechanik) * G.C. Schatz, M.A. Rantner, Quantum Mechanics in Chemistry Skript von Prof. W. Domcke (TU München) * F. Jensen, Intoduction to Computational Chemistry * A. Szabo, N.S. Ostlund, Moder Quantum Chemistry: Introduction to Advanced Electronic Structure Theory * H.-D. Meyer, MCTDH review 2011 Tutorials: Blatt 1 Lösungen Blatt 2, ab 17.11.2011 Lösungen (Teil 1), Lösungen (Teil 2) Blatt 3, ab 1.12.2011 Lösungen Blatt 4, ab 15.12.2011 Lösungen Blatt 5, ab 20.12.2011 Lösungen Weihnachtstest, Lösungen Praktikum: User's Guide MCTDH Mathematics for Chemists, Bachelor chem0102Im Wintersemester 2011/2012 wird Mathemetik für Chemiker von Herrn Prof. Hartke gelesenÜebungsblätter Mathe 1 WS 2010/2011: Blatt 1 Blatt 2 Blatt 3 Blatt 4 Blatt 5 Blatt 6 Blatt 7 Üebungsblätter Mathe 2 SS 2010: Blatt 1 Blatt 2 Blatt 3 Blatt 4 Blatt 5 Blatt 6 Blatt 7 Bachelor/Master thesisfolgende Themen können im Rahmen einer Bachelor- bzw. Masterarbeit bearbeitet werden:possible topics for your bachelor/master thesis with us: * Dynamics and two-dimensional photon-echo spectroscopy at conical intersections * Underdamped vibrations in dynamics and time-resolved spectroscopy of dimers and trimers * Computational design of nanostructures to improve efficiency of organic solar cells * or check our current research projects PraktikaFalls Sie sich für ein Praktikum bei uns interessieren, schreiben Sie mir eine kurze E-MailResearchOverviewCurrent projects Methods Publications OverviewOur research focuses on coherent processes in complex molecular and biological systems and on capabilities of various spectroscopic techniques to detect these processes, as well as to provide information on the underlying dynamical mechanisms. The processes we are interested in (to mention just a few) include ultrafast coherence-driven charge transfer in polyatomic molecules, coherent dynamics at conical intersections, electron-driven proton-transfer processes, as well as coherent energy transfer processes in photosynthetic complexes. Our efforts cover modeling of ultrafast quantum dynamics (coupled electron-nuclear motion), simulations of time- and frequency-resolved spectra (as, e.g., fluorescence up-conversion, pump-probe or photon-echo signals), as well as exploration of coherence control possibilities by means of intense femtosecond laser pulses and plasmonic effects at nanoscale. We are also interested in the interplay between molecular dynamics and nanoplasmons and combine our expertise in these two areas for a variety of purposes as, e.g., improvement of dye-sensitized solar cells performance. Another example among the currently pursued applications concerns the optimization of exciton transport in optoelectronic devices. Nevertheless, method developments remain an essential part of our activities.Current projectsCoherent energy transfer in photosynthetic antennae complexesVibronic effects in two-dimensional photon-echo signals Metal nanoparticles in dye-sensitized solar cells Two-dimensional photon-echo spectroscopy at conical intersections Coherent energy transfer in photosynthetic antennae complexes
Plants and photosynthetic bacteria use complexes built of pigments and proteins to streamline
the transfer of energy from light-harvesting antenna systems, which efficiently capture sunlight,
to the reaction center, in which energy is stored for later use in biochemical processes.
Recently, oscillations in two-dimensional electronic photon-echo spectra of the FMO (Fenna-Matthews-Olson)
photosynthetic complex have been
recorded.
In contrast to the previous findings and assumptions,
these new experimental results suggest a strongly coherent nature of the energy-transfer dynamics which
persists at room temperature as well.
Similar oscillative signals have been reported for algae complexes at room temperatures.
Although these results are extremely intriguing they remain slightly contradictorily and
lack an unambiguous and convincing interpretation.
Our methods allow us to simulate the experimental signals
without any assumptions and approximations with respect to parameters of the involved laser fields.
Therefore, a comparison to the experiment can reveal the validity
of a model employed for the description of the underlying system dynamics.
So far, our calculations demonstrate that the commonly accepted model of the FMO subunit renders a poor agreement
with the first experiment,
but is supported by the more recent experimental results.
To resolve this contradiction we presently
develop more sophisticated models for the system dynamics, as well as theoretically search for the most suitable
schemes for more precise experiments.
Selected Papers:
Vibronic effects in two-dimensional photon-echo signals Two-dimensional (2D) photon-echo (PE) technique in optical domain is based on the same ideas as the 2D
nuclear magnetic resonance (NMR), but in contrast to their NMR counterparts,
the recorded signals are usually very broad and hard to interpret.
The reason for this is that
2D PE in optical domain involves ultrafast transitions between electronic states.
In polyatomic molecules the electronic excitations are usually coupled to many vibrational degrees of freedom.
Upon the action of a short optical pulse vibrational excitations are almost inevitable.
This coupling of electronic and vibrational motion can result in strong vibronic effects on
2D PE signals.
We are currently systemising our findings on these effects to establish
ultimate criteria for identifying vibrational and vibronic features
in electronic 2D PE spectroscopy.
Since electronic 2D PE is designed to provide information on electronic interactions, such a tool for ``ruling out'' the vibrations
is highly relevant and important.
Selected Papers:
Metal nanoparticles in dye-sensitized solar cellsOne of the reasons for a low efficiency of Grätzel dye-sensitized solar cells is too weak absorption of the employed dye molecules. Although there have been some improvements thanks to synthesis modifications, no break through has been yet achieved. It has been demonstrated that metal nanoparticles if put in the vicinity of dye molecules lead to a significant increase of the molecular absorption. Using finite-difference time-domain (FDTD) approach we perform preliminary studies of the efficiency of metal nanoparticles of variable sizes and shapes in enhancing the light absorption by various dyes employed in solar cells of Grätzel type. Our goal is to theoretically optimize the absorption-enhancing metal structures for the most frequently employed and stable dyes.Two-dimensional photon-echo spectroscopy at conical intersectionsIt is well known that conical intersections (CI) between molecular electronic states often drive ultrafast excited-state dynamics and are reponsible for such biological functions as photostability and photoprotection. Penta-fluorobenzene (PFB) and hexa-fluorobenzene (HFB) represent a relatively simple model to study ultrafast dynamics at CIs. There exist several experiments indicating a strongly coherent character of excited-state dynamics in PFB and HFB: apparently, electron transfer in these molecules lead to coherent oscillations in the transients that survive for 1-2~ps. Interestingly, recent pump-probe study of some carotenoids (beta-carotene and lutein) suggests strongly coherent excited-state dynamics as well. We aim to explore the origin and role of coherences in the dynamics at CI of these system and to design two-dimensional photon-echo experiments for verification of theoretical findings.MethodsModeling of ultrafast quantum dynamicsTime- and frequency-resolved nonlinear spectroscopy Modeling of ultrafast quantum dynamics Coherent processes in complex systems require a reliable quantum dynamical description.
The most powerful and accurate tool nowadays is the recently developed multi-layer multi-configurational
time-dependent Hartree approach (ML-MCTDH).
It is a direct wave function description
that allows a numerically exact treatment of hundreds degrees of freedom.
We enjoy a continuous collaboration with the experts of ML-MCTDH
and currently integrate this powerful method in our research.
Up to know multi-level Redfield theory has been our working horse.
In this approach, a partitioning of the overall system into a relevant part
(the 'system') and the remaining degrees of freedom (the 'bath') is employed.
The perturbative treatment of system-bath interaction allows for a computational efficiency and
appears, if accurately implemented, to be a very reliable approximation for the description of
ultrafast multilevel dissipative dynamics.
Fortunately,
complex multidimensional systems can be often realistically described by this reduced density-matrix formalism.
It is very advantageous if only few degrees of freedom
are strongly coupled and mainly determine the system dynamics.
Selected Papers:
Time- and frequency-resolved nonlinear spectroscopyThere is a huge variety of experimental techniques in the field of time- and frequency-resolved optical spectroscopy available nowadays. For the monitoring of electronic-state population dynamics and vibrational wave-packet dynamics in real time, the transient transmittance pump-probe, time- and frequency-gated spontaneous emission or time-resolved coherent anti-Stokes Raman scattering (CARS) techniques are most suitable. Numerous photon-echo techniques (such as two- and three-pulse photon echo, transient grating, three-pulse photon-echo peak shift) are employed for studies of solvation dynamics and the determination of electronic dephasing times. Two-dimensional photon-echo spectroscopy has been recently extended to the visible range and appears to be especially sensitive to electronic and vibronic couplings and allows to monitor the system coherences in real time. While pump-probe, CARS and photon echo are examples of so-called four-wave mixing (4WM) schemes, a number of six-wave mixing (6WM) experiments and 4WM-6WM interferometry have been realized as well. Although modern experiments provide an immense amount of information, the latter often remains indirect and requires a detailed analysis for an unambiguous interpretation. The measured time- and frequency-resolved signals depend both on the system dynamics and on the laser pulse properties, and their interpretation may become particularly difficult if many coupled degrees of freedom are involved in the process under study. Proper simulations of the signals are thus necessary to facilitate interpretation of experimental results, and to provide guidance for further investigations. Recently, we have proposed several efficient methods for calculation of the time- and frequency-resolved optical signals. The methods allow for system Hamiltonians of arbitrary complexity, have no limitations with respect to pulse durations and automatically account for pulse-overlap effects. At present we are able to accurately and efficiently calculate observables of all the most frequently employed investigation schemes: time- and frequency-resolved fluorescence and N-wave-mixing (NWM) spectroscopy. The most universal tool is the equation-of- motion phase-matching approach (EOM-PMA). It allows for a straightforward calculation of any N-wave mixing signal and can be implemented within various dynamical descriptions based either on density-matrix or wave-function formalisms. EOM-PMA has been implemented for simulations of homodyne and heterodyne two-dimensional photon-echo signals by several research groups. The non- perturbative doorway-window approach (NP-DWA) is the alternative to employ in case of strong fields (valid in the limit of non-overlapping pulses). The developed two- pulse schemes provide an easy way to calculate fluorescence up-conversion and pump-probe observables for pump pulses of arbitrary strength.Selected Papers:
Publications201225. M. Gelin, L. Sharp, D. Egorova, W. Domcke, Bath-induced correlations and relaxation of vibronic dimers, J. Chem. Phys. 136 (2012) 034507.24. M. Gelin, D. Egorova, W. Domcke, Efficient Methods for Computation of Ultrafast Time- and Frequency-Resolved Spectroscopic Signals in ``Computational Strategies for Spectroscopy'' by V. Barone (ed.), J.Wiley & Sons, 2012 201123. M. Gelin, D. Egorova, W. Domcke, Exact quantum master equation for a molecular aggregate coupled to a harmonic bath, Phys. Rev. E, 84 (2011) 041139.22. M. Gelin, D. Egorova, W. Domcke, Strong and Long Makes Short: Strong-Pump Strong-Probe Spectroscopy, J. Phys. Chem. Lett. 2 (2011) 114. 21. M. Gelin, D. Egorova, W. Domcke, Optical N-Wave-Mixing Spectroscopy with Strong and Temporally Well-Separated Pulses: The Doorway-Window Representation, J. Phys. Chem. B 115 (2011) 5648. 201020. L. Sharp, D. Egorova, W. Domcke, Coherent energy transfer in photosynthesis: simulations of 2D electronic photon-echo spectra of the FMO subunit, J. Chem. Phys. 132 (2010) 014501.200919. M. Gelin, D. Egorova, W. Domcke, Efficient calculation of the polarization induced by N coherent laser pulses, J. Chem. Phys. 131 (2009) 194103.18. M. Gelin, D. Egorova, W. Domcke, Manipulating electronic couplings and nonadiabatic nuclear dynamics with strong laser pulses, J. Chem. Phys. 131 (2009) 124505. 17. M. Gelin, D. Egorova, W. Domcke, Efficient Calculation of Time- and Frequency-Resolved Four-Wave-Mixing Signals, Acc. Chem. Res.42 (2009) 1290. 200816. D. Egorova, M. Gelin, M. Thoss, H. Wang, W. Domcke, Effects of intense femtosecond pumping on multilevel ultrafast dynamics with relaxation, J. Chem. Phys. 129 (2008) 214303.15. D. Egorova, Detection of electronic and vibrational coherences in molecular systems by 2D electronic photon echo spectroscopy, Chem. Phys. 347 (2008) 166 (W. Domcke Special Issue). 200714. D. Egorova, M. Gelin, W. Domcke, Analysis of vibrational coherences in homodyne and two-dimensional heterodyne photon-echo spectra of Nile Blue, Chem. Phys. 341 (2007) 113 (D. A. Wiersma Special Issue).13. D. Egorova, M. Gelin, W. Domcke, Analysis of cross peaks in two-dimensional electronic photon-echo spectroscopy for simple models with vibrations and dissipation, J. Chem. Phys. 126 (2007) 074314. 200512. D. Egorova, M. Gelin, W. Domcke, Efficient method for the calculation of time- and frequency-resolved four-wave mixing signals and its application to photon-echo spectroscopy, J. Chem. Phys. 123 (2005) 164112.11. M. Gelin, D. Egorova, A. Pisliakov, W. Domcke, Transient phenomena in time- and frequency-gated spontaneous emission, J. Phys. Chem. A 109 (2005) 3587. 10. D. Egorova, M. Gelin, W. Domcke, Time- and frequency-resolved fluorescence spectra of nonadiabatic dissipative systems: what photons can tell us , J. Chem. Phys. 122 (2005) 134504. 9. M. Gelin, D. Egorova, W. Domcke, A new method for the calculation of two-pulse time- and frequency-resolved spectra, Chem. Phys. 312 (2005) 135 20048. M. Gelin, D. Egorova, A. Pisliakov, W. Domcke, Unified description of sequential and coherent contributions to time-resolved spontaneous emission signals: generalized doorway-window approach, Chem. Phys. Lett. 391 (2004) 234.7. M. Gelin, D. Egorova, W. Domcke, Time-resolved spontaneous emission beyond the doorway-window approximation, Chem. Phys. 301 (2004) 129. 6. D. Egorova, W. Domcke, Quantum dynamical simulations of ultrafast photoinduced electron-transfer processes, J. Photochem. Photobiol. A 166 (2004) 19. 5. D. Egorova, W. Domcke, Coherent vibrational dynamics during ultrafast photoinduced electron-transfer reactions: quantum dynamical simulations within multi-level Redfield theory, Chem. Phys. Lett. 384 (2004) 157. 20034. D. Egorova, M. Thoss, H. Wang, W. Domcke, Modeling of ultrafast electron-transfer processes: validity of multi-level Redfield theory, J. Chem. Phys. 119 (2003) 2761.3. M. Gelin, A.V. Pisliakov, D. Egorova, W. Domcke, A simple model for the calculation of nonlinear optical response functions and femtosecond time-resolved spectra, J. Chem. Phys. 118 (2003) 5287. 20012. D. Egorova, A. Kühl, W. Domcke, Modeling of ultrafast electron-transfer dynamics: multi-level Redfield theory and validity of approximations, Chem. Phys. 268 (2001) 105.1. A.K. Belyaev, D. Egorova, J. Grosser, T. Menzel, Electron transition and asymptotic couplings in low-energy atomic collisions, Phys. Rev. A 64 (2001) 052701. |
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