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Coherence transfer during relaxation in molecular aggregates
Olšina, Jan ; Mančal, Tomáš (advisor) ; Skála, Lubomír (referee)
We study the time dependence of the density operator of molecular aggregates in contact with thermal bath, to find a proper approximation for the description of a coherence transfer influence on this evolution. It is based on results of the computer program, written by the author of the work. The program uses three methods of evaluation - the solution of the convolution Quantum Master Equation, and solution of the derived Redfield equations in Markov and subsequent Secular approximations. The temperature dependence and dependence on other parameters of the model are discussed on the basis of the obtained numerical results performed on an example of a trimer. The influence of coherence transfer on time-evolution superoperator of the trimer is discussed as well. The reasons why the Markov approximation fails for a wide spectrum of parameters are given. It is concluded that it is not suitable for the description of coherence transfer effects.
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Přenos koherencí při relaxaci excitační energie v molekulárních agregátech
Olšina, Jan ; Mančal, Tomáš (advisor)
We study the time dependence of the density operator of molecular aggregates in contact with thermal bath, to find a proper approximation for the description of a coherence transfer influence on this evolution. It is based on results of the computer program, written by the author of the work. The program uses three methods of evaluation - the solution of the convolution Quantum Master Equation, and solution of the derived Redfield equations in Markov and subsequent Secular approximations. The temperature dependence and dependence on other parameters of the model are discussed on the basis of the obtained numerical results performed on an example of a trimer. The influence of coherence transfer on time-evolution superoperator of the trimer is discussed as well. The reasons why the Markov approximation fails for a wide spectrum of parameters are given. It is concluded that it is not suitable for the description of coherence transfer effects.
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Theory of Relaxation and Energy Transfer in Open Quantum Systems
Olšina, Jan ; Mančal, Tomáš (advisor) ; Valkunas, Leonas (referee) ; Szöcs, Vojtech (referee)
The work summarizes basic theory of relaxation, energy transfer and decoher- ence in photosynthetic molecular aggregates described as open quantum systems and basic theory of third order coherent non-linear spectroscopy. The work presents two methods for calculation of photo-induced dynamics of molecular aggregates. The methods relax certain approximations of the theories commonly used to model the relaxation and energy transfer in the molecular systems on the sub-picosecond time scale. The first theory derived in the formalism of para- metric projection operators accounts for correlations in a second-order non-linear response-function that are usually neglected in the formalism of master equations. The second theory represents stochastic model of exact dynamics via the cumulant expansion. The work also presents an analysis of importance of the secular and the Markov approximations in the description of dynamics derived in the second-order perturbation theory in the system-bath coupling with emphasis on the excitonic coherence lifetime.
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Přenos koherencí při relaxaci excitační energie v molekulárních agregátech
Olšina, Jan ; Mančal, Tomáš (advisor)
We study the time dependence of the density operator of molecular aggregates in contact with thermal bath, to find a proper approximation for the description of a coherence transfer influence on this evolution. It is based on results of the computer program, written by the author of the work. The program uses three methods of evaluation - the solution of the convolution Quantum Master Equation, and solution of the derived Redfield equations in Markov and subsequent Secular approximations. The temperature dependence and dependence on other parameters of the model are discussed on the basis of the obtained numerical results performed on an example of a trimer. The influence of coherence transfer on time-evolution superoperator of the trimer is discussed as well. The reasons why the Markov approximation fails for a wide spectrum of parameters are given. It is concluded that it is not suitable for the description of coherence transfer effects.
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Coherence transfer during relaxation in molecular aggregates
Olšina, Jan ; Mančal, Tomáš (advisor) ; Skála, Lubomír (referee)
We study the time dependence of the density operator of molecular aggregates in contact with thermal bath, to find a proper approximation for the description of a coherence transfer influence on this evolution. It is based on results of the computer program, written by the author of the work. The program uses three methods of evaluation - the solution of the convolution Quantum Master Equation, and solution of the derived Redfield equations in Markov and subsequent Secular approximations. The temperature dependence and dependence on other parameters of the model are discussed on the basis of the obtained numerical results performed on an example of a trimer. The influence of coherence transfer on time-evolution superoperator of the trimer is discussed as well. The reasons why the Markov approximation fails for a wide spectrum of parameters are given. It is concluded that it is not suitable for the description of coherence transfer effects.
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