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Electronic Structure Theory has led to a variety of developments and applications. In the Nooijen group the focus is on the development and use of Coupled Cluster based approaches. Coupled Cluster is a very strong and accurate approach to the quantum mechanical problem. The research results presented in the thesis testify to the Similarity Transformed Equation of Motion Coupled Cluster (STEOM-CC) for being a very accurate and yet computationally inexpensive approach for excited states. This study reveals new features about STEOM and provides promise regarding future improvement in the methodology. STEOM can be used as the first step in the construction of the Vibronic model, which is a strong tool to move to paradigms beyond the Born-Oppenheimer approximation. Spin-Orbit Coupling (SOC) is a very important ingredient required to study relativistic phenomena and its quantum mechanical implementation for many body systems is not straightforward. The most widely used SOC operator in Chemical Physics is the Breit-Pauli operator, which requires employing non-trivial approximations to the Dirac equation to adapt the theory to many body systems. The integration of electronic structure approaches, Vibronic Coupling, and SOC is essential to study the phenomenon of intersystem crossing (transition between spin states) in fine detail. In this thesis a computational benchmark of STEOM is discussed, while the frameworks of Vibronic Coupling and Spin-Orbit Coupling (SOC) are considered on a theoretical level.

Electronic Structure Theory has led to a variety of developments and applications. In the Nooijen group the focus is on the development and use of Coupled Cluster based approaches. Coupled Cluster is a very strong and accurate approach to the quantum mechanical problem. The research results presented in the thesis testify to the Similarity Transformed Equation of Motion Coupled Cluster (STEOM-CC) for being a very accurate and yet computationally inexpensive approach for excited states. This study reveals new features about STEOM and provides promise regarding future improvement in the methodology. STEOM can be used as the first step in the construction of the Vibronic model, which is a strong tool to move to paradigms beyond the Born-Oppenheimer approximation. Spin-Orbit Coupling (SOC) is a very important ingredient required to study relativistic phenomena and its quantum mechanical implementation for many body systems is not straightforward. The most widely used SOC operator in Chemical Physics is the Breit-Pauli operator, which requires employing non-trivial approximations to the Dirac equation to adapt the theory to many body systems. The integration of electronic structure approaches, Vibronic Coupling, and SOC is essential to study the phenomenon of intersystem crossing (transition between spin states) in fine detail. In this thesis a computational benchmark of STEOM is discussed, while the frameworks of Vibronic Coupling and Spin-Orbit Coupling (SOC) are considered on a theoretical level.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第17595号 / 工博第3754号 / 新制||工||1572(附属図書館) / 30361 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 伊藤 紳三郎, 教授 赤木 和夫, 教授 金谷 利治 / 学位規則第4条第1項該当

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24903号 / 工博第5183号 / 新制||工||1989(附属図書館) / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 梶 弘典, 教授 関 修平, 教授 寺村 謙太郎 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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Les travaux présentés dans cette thèse peuvent être divisés en deux parties. Dans une première partie, nous avons étudié le processus de photoisomérisation dans plusieurs systèmes. Une analyse de structure électronique accompagnée d’un calcul préliminaire de dynamique semi-classique ont été appliqué à un modèle minimal du rétinal afin d’extraire les degrés de libertés les plus importants lors de l’isomérisation. Cela dans le but de construire des surfaces d’énergie potentielle diabatiques pour effectuer une étude de dynamique quantique. Une approche de type dynamique semi-classique a été appliquée à un modèle de moteur moléculaire dans le but d’étudier l’origine de l’uni-directionalité de sa rotation. Finalement, une étude de structure électronique d’un complexe de Rhénium contenant un ligand de type rétinal a été effectué pour étudier l’influence du métal sur la spectroscopie du ligand rétinal. Dans une deuxième partie nous nous sommes intéressés à l’étude des croisements intersystème dans un complexe de Rhénium. Afin de pouvoir apporter une explication à un comportement contrintuitif de ce complexe, nous avons développé un Hamiltonien modèle capable de tenir compte des couplages vibroniques interétats et spin-orbit. Cet Hamiltonien a été testé sur ce-dit système, et nous a permis, grâce à une étude de structure électronique de proposer un mécanisme de relaxation différent de celui proposé expérimentalement. / This thesis can be divided in two parts.In the first one, we have studied the photoisomerization process in several systems. An electronic structure analysis mixed with a preliminary semi-classical dynamics investigation has been applied to a minimal model of the retinal chromophore in order to select the most important degrees of freedom involved in the process. The goal of this is to build diabatic potential energy surfaces in order to conduct quantum dynamics simulations. A semi-classical approach has also been applied to a molecular motor model to study the origin of the unidirectionality of its rotary motion. Finally, an electronic structure of a rhenium complex with a retinal-like ligand has been performed to study the effect of the coordination to a metallic atom on the spectroscopy of the retinal ligand. In the second part, we have investigated the intersystem crossings in a rhenium complex. In order to bring an explanation to an experimentally observed conterintuitive behavior of this complex, we have developed a model Hamiltonian that includes both interstate vibronic coupling and spin-orbit coupling. This Hamiltonian has been tested on the said complex and, in complement to an electronic structure study, allowed us to formulate a decay mechanism different from the one proposed based on experiments.

Title: Theoretical study of spin-orbit coupling on spectra and photophysics of rhenium complexes Author: RNDr. Radka Heydová Department: Physical and Macromolecular Chemistry Supervisor: Ing. Stanislav Záliš, CSc., JHI AS CR, v.v.i. Supervisor's e-mail address: stanislav.zalis@jh.inst-cas.cz Abstract: Relativistic effects, especially spin-orbit coupling (SOC), play an essential role in transition metal chemistry and SOC treatment is indispensable for a correct theoretical description. To demonstrate the importance of SOC, the energies and oscillator strengths of vertical transitions for a series of [ReX(CO)3(2,2'-bipyridine)] (X = Cl, Br, I) and [Re(imidazole)(CO)3(1,10-phenanthroline)]+ complexes were calculated in the spin-free (SF) and spin-orbit (SO) conceptual frameworks. Two different computational approaches were adopted: SO-MS-CASPT2 where SOC was added a posteriori using a configuration interaction model (SO-RASSI), and the approximate perturbative SO-TD-DFT method. Relativistic effects were included via the two-component Douglas-Kroll-Hess transformation and the zeroth-order regular approximation in the former and the latter technique, respectively. The SF (i.e. accounting only for the scalar relativistic effects) and SO results from both methods were compared with each other and to available...

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