Dissertations / Theses: 'Time-dependent density functional theory'

1

Yam, Chi-yung, and 任志勇. "Linear-scaling time-dependent density functional theory." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31246199.

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Cazorla, Julien J. A. "Real time techniques in time-dependent density functional theory." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615790.

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Ioannou, Andrew George. "Applications of time-dependent current density functional theory." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624734.

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Van, Caillie Carole. "Electronic structure calculations using time-dependent density functional theory." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621205.

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Esplugas, Ricardo Oliveira. "Density functional theory and time-dependent density functional theory studies of copper and silver cation complexes." Thesis, University of Sussex, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496931.

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A particular emphasis of this thesis has been to provide insight into the underlying stability of these complexes and hence interpret experimental data, and to establish the development of solvation shell structure and its effect on reactivity and excited states. Energy decomposition analysis, fragment analysis and charge analysis has been used throughout to provide deeper insight into the nature of the bonding in these complexes. This has also been used successfully to explain observed preferential stability and dissociative loss products.

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Lacombe, Lionel. "On dynamics beyond time-dependent mean-field theories." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30185/document.

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Cette thèse présente différentes approches quantiques pour l'exploration de processus dynamiques dans des systèmes multiélectroniques, en particulier après une forte excitation qui peut aboutir à des effets dissipatifs. Les théories de champ moyen sont un outil utile à cet égard. Malgré l'existence de nombreux travaux réalisés ces deux dernières décennies, ces théories peinent à reproduire complètement la corrélation à deux corps. La thermalisation est un des effets des collisions électron-électron. Après un chapitre introductif, on présentera dans le chapitre 2 le formalisme de plusieurs méthodes étudiées dans cette thèse, ayant pour but la description de ces effets en ajoutant un terme de collision au champ moyen. Ces méthodes sont appelées Stochastic Time-Dependent Hartree Fock (STDHF), Extended TDHF (ETDHF) et Collisional TDHF (CTDHF). Cette dernière méthode représente d'une certaine façon le résultat principal de cette thèse. L'implémentation numérique de chacune de ces méthodes sera aussi examinée en détail. Dans les chapitres 3, 4 et 5, nous appliquerons à différents systèmes les méthodes présentées dans le chapitre 2. Dans le chapitre 3, nous étudions d'abord un canal de réaction rare, ici la probabilité d'un électron de s'attacher à un petit agrégat d'eau. Un bon accord avec les données expérimentales a été observé. Dans le chapitre 4, un modèle fréquemment utilisé en physique nucléaire est résolu exactement et comparé quantitativement à STDHF. L'évolution temporelle des observables à un corps s'accorde entre les deux méthodes, plus particulièrement en ce qui concerne le comportement thermique. Néanmoins, pour permettre une bonne description de la dynamique, il est nécessaire d'avoir une grande statistique, ce qui peut être un frein à l'utilisation de STDHF sur de larges systèmes. Pour surpasser cette difficulté, dans le chapitre 5 nous testons CTDHF, qui a été introduit dans le chapitre 2, sur un modèle à une dimension (et sans émission électronique). Le modèle se compose d'électrons dans un potentiel de type jellium avec une interaction auto-cohérente sous la forme d'une fonctionnelle de la densité. L'avantage de ce modèle à une dimension est que les calculs STDHF sont possibles numériquement, ce qui permet une comparaison directe aux calculs CTDHF. Dans cette étude de validité du concept, CTDHF s'accorde remarquablement bien avec STDHF. Cela pose les jalons pour une description efficace de la dissipation dans des systèmes réalistes en trois dimensions par CTDHF
This thesis presents various quantal approaches for the exploration of dynamical processes in multielectronic systems, especially after an intense excitation which can possibly lead to dissipative effects. Mean field theories constitute useful tools in that respect. Despite the existence of numerous works during the past two decades, they have strong difficulties to capture full 2-body correlations. Thermalization is one of these effects that stems from electron-electron collisions. After an introductory chapter, we present in Chapter 2 the formalism of the various schemes studied in this thesis toward the description of such an effect by including collisional terms on top of a mean field theory. These schemes are called Stochastic Time-Dependent Hartree Fock (STDHF), Extended TDHF (ETDHF) and Collisional TDHF (CTDHF). The latter scheme constitutes in some sense the main achievement of this thesis. The numerical realizations of each scheme are also discussed in detail. In Chapters 3, 4 and 5, we apply the approaches discussed in Chapter 2 but in various systems. In Chapter 3, we first explore a rare reaction channel, that is the probability of an electron to attach on small water clusters. Good agreement with experimental data is achieved. In Chapter 4, a model widely used in nuclear physics is exactly solved and quantitatively compared to STDHF. The time evolution of 1-body observables agrees well in both schemes, especially what concerns thermal behavior. However, to allow a good description of the dynamics, one is bound to use a large statistics, which can constitute a hindrance of the use of STDHF in larger systems. To overcome this problem, in Chapter 5, we go for a testing of CTDHF developed in Chapter 2 in a one-dimensional system (and without electronic emission). This system consists in electrons in a jellium potential with a simplified self-consistent interaction expressed as a functional of the density. The advantage of this 1D model is that STDHF calculations are numerically manageable and therefore allows a direct comparison with CTDHF calculations. In this proof of concept study, CTDHF compares remarkably well with STDHF. This thus paves the road toward an efficient description of dissipation in realistic 3D systems by CTDHF

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7

Jensen, Daniel S. "Real-Space Approach to Time Dependent Current Density Functional Theory." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2559.

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A real-space time-domain calculation of the frequency-dependent dielectric constant of nonmetallic crystals is outlined and the integrals required for this calculation are computed. The outline is based on time dependent current density functional theory and is partially implemented in the ab initio density functional theory FIREBALL program. The addition of a vector potential to the Hamiltonian of the system is discussed as well as the need to include the current density in addition to the particle density. The derivation of gradient integrals within a localized atomic-like orbital basis is presented for use in constructing the current density. Due to the generality of the derivation we also give the derivation of the kinetic energy, dipole, and overlap interactions.

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Tempel, David Gabriel. "Time-Dependent Density Functional Theory for Open Quantum Systems and Quantum Computation." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10208.

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First-principles electronic structure theory explains properties of atoms, molecules and solids from underlying physical principles without input from empirical parameters. Time-dependent density functional theory (TDDFT) has emerged as arguably the most widely used first-principles method for describing the time-dependent quantum mechanics of many-electron systems. In this thesis, we will show how the fundamental principles of TDDFT can be extended and applied in two novel directions: The theory of open quantum systems (OQS) and quantum computation (QC). In the first part of this thesis, we prove theorems that establish the foundations of TDDFT for open quantum systems (OQS-TDDFT). OQS-TDDFT allows for a first principles description of non-equilibrium systems, in which the electronic degrees of freedom undergo relaxation and decoherence due to coupling with a thermal environment, such as a vibrational or photon bath. We then discuss properties of functionals in OQS-TDDFT and investigate how these differ from functionals in conventional TDDFT using an exactly solvable model system. Next, we formulate OQS-TDDFT in the linear-response regime, which gives access to environmentally broadened excitation spectra. Lastly, we present a hybrid approach in which TDDFT can be used to construct master equations from first-principles for describing energy transfer in condensed phase systems. In the second part of this thesis, we prove that the theorems of TDDFT can be extended to a class of qubit Hamiltonians that are universal for quantum computation. TDDFT applied to universal Hamiltonians implies that single-qubit expectation values can be used as the basic variables in quantum computation and information theory, rather than wavefunctions. This offers the possibility of simplifying computations by using the principles of TDDFT similar to how it is applied in electronic structure theory. Lastly, we discuss a related result; the computational complexity of TDDFT.
Physics

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9

Zhang, Xing. "Spin-flip time-dependent density functional theory and its applications to photodynamics." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469628877.

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Tafur, Sergio. "NONLINEAR OPTICAL PROPERTIES OF ORGANIC CHROMOPHORES CALCULATED WITHIN TIME DEPENDENT DENSITY FUNCTIONAL THEORY." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4079.

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Time Dependent Density Functional Theory offers a good accuracy/computational cost ratio among different methods used to predict the electronic structure for molecules of practical interest. The Coupled Electronic Oscillator (CEO) formalism was recently shown to accurately predict Nonlinear Optical (NLO) properties of organic chromophores when combined with Time Dependent Density Functional Theory. Unfortunately, CEO does not lend itself easily to interpretation of the structure activity relationships of chromophores. On the other hand, the Sum Over States formalism in combination with semiempirical wavefunction methods has been used in the past for the design of simplified essential states models. These models can be applied to optimization of NLO properties of interest for applications. Unfortunately, TD-DFT can not be combined directly with SOS because state-to-state transition dipoles are not defined in the linear response TD approach. In this work, a second order CEO approach to TD-DFT is simplified so that properties of double excited states and state-to-state transition dipoles may be expressed through the combination of linear response properties. This approach is termed the a posteriori Tamm-Dancoff approximation (ATDA), and validated against high-level wavefunction theory methods. Sum over States (SOS) and related Two-Photon Transition Matrix formalism are then used to predict Two-Photon Absorption (2PA) profiles and anisotropy, as well as Second Harmonic Generation (SHG) properties. Numerical results for several conjugated molecules are in excellent agreement with CEO and finite field calculations, and reproduce experimental measurements well.
M.S.
Department of Physics
Sciences
Physics MS

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11

Rocca, Dario. "Time-Dependent Density Functional Perturbation Theory: new algorithms with applications to molecular spectra." Doctoral thesis, SISSA, 2007. http://hdl.handle.net/20.500.11767/3936.

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This thesis is organized as follows. In Chapter 1 we will illustrate the basic concepts of DFT and TDDFT; the most common computational approaches will be also considered. In Chapter 2 our new formalism will be introduced together with the numerical algorithm and a first application to benzene. In chapter 3 we will illustrate a technique for extrapolating the Lanczos coefficients and to accelerate the convergence of the method. The resulting methodology will be applied to more challenging problems, such as fullerene and chlorophyll spectra. In Chapter 4 the method will be applied to the study of dye-sensitized solar cells. In appendix A and B we will give the technical details of our specific implementation in the plane-wave pseudopotential framework.

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Craig, Colleen F. "Nonadiabatic molecular dynamics in time-dependent density functional theory with applications to nanoscale materials /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8671.

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Drummond, Michael L. "Denisty functional theory investigations of the ground- and excited-state chemistry of dinuclear organometallic carbonyls." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1104284754.

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Dinh, Phuong Mai. "Time-dependent density functional theory applied to clusters and molecules in contact with an environment." Habilitation à diriger des recherches, Université Paul Sabatier - Toulouse III, 2009. http://tel.archives-ouvertes.fr/tel-00981941.

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We present recent theoretical and methodological explorations on the dynamics of sodium clusters in the framework of Time-Dependent Density Functional Theory (TDDFT), coupled non-adiabatically to Molecular-Dynamics (MD). In particular, a hierarchical approach, in the spirit of Quantum-Mechanical/Molecular-Mechanical methods, has been developed for the description of metal clusters in interaction with a dynamically polarizable substrate, as rare gases or MgO. Numerous examples of application of this approach (Na clusters in or on Ar substrate, Na clusters deposited on MgO; optical response, dynamical deposition, laser irradiation, ...) are reviewed. We also briefly discuss complementing research activities. Formal developments on the Self-Interaction Correction issue in DFT and TDDFT are discussed in a word. We have furthermore extended our TDDFT-MD theory to the case of organic (C, N, O, H made) systems and a few examples of investigated dynamical processes are presented. Recent calculations of photoelectron angular distributions of free metal clusters are reported as well. We finally sketch with some perspectives for the years to come.

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15

Niesert, Manfred [Verfasser]. "Ab initio calculations of spin-wave excitation spectra from time-dependent density-functional theory / Manfred Niesert." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2012. http://d-nb.info/102156754X/34.

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Hofmann, Fabian [Verfasser], and Stephan [Akademischer Betreuer] Kümmel. "The Sternheimer Approach to Linear Response Time-Dependent Density Functional Theory / Fabian Hofmann ; Betreuer: Stephan Kümmel." Bayreuth : Universität Bayreuth, 2020. http://d-nb.info/1223982041/34.

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Hofmann-Mees, Dirk [Verfasser], and Stephan [Akademischer Betreuer] Kümmel. "Charge and excitation-energy transfer in time-dependent density functional theory / Dirk Hofmann-Mees. Betreuer: Stephan Kümmel." Bayreuth : Universität Bayreuth, 2013. http://d-nb.info/1059353652/34.

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18

Zhu, Ying. "A Comparison of Calculation by Real-Time and by Linear-Response Time-Dependent Density Functional Theory in the Regime of Linear Optical Response." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1460554444.

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Richard, Ryan M. "Time-Dependent Density-Functional Description of the ¹L_a State in Polycyclic Aromatic Hydrocarbons." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1302098974.

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Bhandari, Srijana. "AN ELECTRONIC STRUCTURE APPROACH TO UNDERSTAND CHARGE TRANSFERAND TRANSPORT IN ORGANIC SEMICONDUCTING MATERIALS." Kent State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=kent1606836665551399.

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Robinson, Mark. "Accessing large length and time scales with density functional theory." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609128.

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Maier, Toni Mike [Verfasser], Martin [Akademischer Betreuer] Kaupp, Martin [Gutachter] Kaupp, and Thomas [Gutachter] Körzdörfer. "Development of local hybrid functionals for time-dependent density functional theory / Toni Mike Maier ; Gutachter: Martin Kaupp, Thomas Körzdörfer ; Betreuer: Martin Kaupp." Berlin : Technische Universität Berlin, 2016. http://d-nb.info/1156011787/34.

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Rüger, Robert, Lenthe Erik van, Thomas Heine, and Lucas Visscher. "Tight-binding approximations to time-dependent density functional theory: A fast approach for the calculation of electronically excited states." AIP Publishing, 2016. https://ul.qucosa.de/id/qucosa%3A21501.

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We propose a new method of calculating electronically excited states that combines a density functional theory based ground state calculation with a linear response treatment that employs approximations used in the time-dependent density functional based tight binding (TD-DFTB) approach. The new method termed time-dependent density functional theory TD-DFT+TB does not rely on the DFTB parametrization and is therefore applicable to systems involving all combinations of elements. We show that the new method yields UV/Vis absorption spectra that are in excellent agreement with computationally much more expensive TD-DFT calculations. Errors in vertical excitation energies are reduced by a factor of two compared to TD-DFTB.

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Jokar, Jeiran Verfasser], Nicole [Akademischer Betreuer] Helbig, and Carsten [Akademischer Betreuer] [Honerkamp. "Adiabatic approximations within time-dependent density functional theory for the non-linear regime / Jeiran Jokar ; Nicole Helbig, Carsten Honerkamp." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1161411771/34.

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Jokar, Jeiran [Verfasser], Nicole Akademischer Betreuer] Helbig, and Carsten [Akademischer Betreuer] [Honerkamp. "Adiabatic approximations within time-dependent density functional theory for the non-linear regime / Jeiran Jokar ; Nicole Helbig, Carsten Honerkamp." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1161411771/34.

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Betzinger, Markus [Verfasser]. "Orbital-dependent exchange-correlation functionals in density-functional theory realized by the FLAPW method / Markus Betzinger." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2012. http://d-nb.info/1022854364/34.

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27

Wang, Yuekui [Verfasser]. "Application of the Time-Dependent Density Functional Theory to the Study of Chiroptical Properties of Organic and Inorganic Compounds / Yuekui Wang." Aachen : Shaker, 2003. http://d-nb.info/1170543413/34.

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Falklöf, Olle, and Bo Durbeej. "Modeling of phytochrome absorption spectra." Linköpings universitet, Beräkningsfysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-92393.

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Phytochromes constitute one of the six well-characterized families of photosensory proteins in Nature. From the viewpoint of computational modeling, however, phytochromes have been the subject of much fewer studies than most other families of photosensory proteins, which is likely a consequence of relevant high-resolution structural data becoming available only in recent years. In this work, hybrid quantum mechanics/molecular mechanics (QM/MM) methods are used to calculate UV-vis absorption spectra of Deinococcus radiodurans bacteriophytochrome. We investigate how the choice of QM/MM methodology affects the resulting spectra and demonstrate that QM/MM methods can reproduce the experimental absorption maxima of both the Q and Soret bands with an accuracy of about 0.15 eV. Furthermore, we assess how the protein environment influences the intrinsic absorption of the bilin chromophore, with particular focus on the Q band underlying the primary photochemistry of phytochromes.

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Weerawardene, K. L. Dimuthu M. "Optical and luminescence properties of noble metal nanoparticles." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/38189.

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Doctor of Philosophy
Department of Chemistry
Christine M. Aikens
The remarkable optical and luminescence properties of noble metal nanoparticles (with diameters < 2 nm) attract researchers due to potential applications in biomedicine, photocatalysis, and optoelectronics. Extensive experimental investigations on luminescence properties of thiolate-protected gold and silver nanoclusters during the past decade have failed to unravel their exact photoluminescence mechanism. Herein, density functional and time-dependent density functional theory (DFT and TDDFT) calculations are performed to elucidate electronic-level details of several such systems upon photoexcitation. Multiple excited states are found to be involved in photoemission from Au₂₅(SR)₁₈– nanoclusters, and their energies agree well with experimental emission energies. The Au₁₃ core-based excitations arising due to electrons excited from superatom P orbitals into the lowest two superatom D orbitals are responsible for all of these states. The large Stokes shift is attributed to significant geometrical and electronic structure changes in the excited state. The origin of photoluminescence of Ag₂₅(SR)₁₈– nanoclusters is analogous to their gold counterparts and heteroatom doping of each cluster with silver and gold correspondingly does not affect their luminescence mechanism. Other systems have been examined in this work to determine how widespread these observations are. We observe a very small Stokes shift for Au₃₈(SH)₂₄ that correlates with a relatively rigid structure with small bond length changes in its Au₂₃ core and a large Stokes shift for Au₂₂(SH)₁₈ with a large degree of structural flexibility in its Au₇ core. This suggests a relationship between the Stokes shift of gold−thiolate nanoparticles and their structural flexibility upon photoexcitation. The effect of ligands on the geometric structure and optical properties of the Au₂₀(SR)₁₆ nanocluster is explored. Comparison of the relative stability and optical absorption spectra suggests that this system prefers the [Au₇(Au₈SR₈)(Au₃SR₄)(AuSR₂)₂] structure regardless of whether aliphatic or aromatic ligands are employed. The real-time (RT) TDDFT method is rapidly gaining prominence as an alternative approach to capture optical properties of molecular systems. A systematic benchmark study is performed to demonstrate the consistency of linear-response (LR) and RT-TDDFT methods for calculating the optical absorption spectra of a variety of bare gold and silver nanoparticles with different sizes and shapes.

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Natarajan, Bhaarathi. "Implémentation et applications d'algorithmes fondés sur la théorie de la fonctionnelle de la densité dépendante du temps dans les logiciels à la base des fonctions gaussiennes et ondelettes." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00682011.

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L'interaction entre la matière et le rayonnement est un domaine bien établi de la physique. Pour un physico-chimiste, cette interaction peut être utilisée comme une sonde (spectroscopie) ou pour provoquer des réactions chimiques (photo-chimie). Les mécanismes des réactions photochimiques sont difficiles à étudier expérimentalement et même les études les plus sophistiquées de spectroscopies femtosecondes peuvent bénéficier énormément des simulations théoriques.Les résultats spectroscopiques d'ailleurs ont souvent besoin des calculs théoriques pour l'analyse de leurs spectres. Les méthodes théoriques pour décrire les processus photochimiques ont été principalement développées en utilisant le concept de la fonction d'onde à N corps et ont eu des succès remarquables. Cependant de telles approches sont généralement limitées à des petites ou moyennes molécules. Heureusement la théorie de la fonctionnelle de la densité dépendant du temps (TD-DFT) a émergé comme une méthode simple de calcul pouvant être appliquée à des molécules plus grandes, avec une précision qui est souvent, mais pas toujours, semblable à la précision provenant des méthodes basés sur la fonction d'onde à N électrons. Une partie de cette thèse consiste à surmonter les difficultés des approximations utilisées de nos jours en TD-DFT. En particulier, nous avons examiné la qualité des intersections coniques quand l'approche du retournement de spin non collinéaire de Ziegler-Wang est utilisée et nous avons montré que l'approche du retournement de spin, parfois ,améliore dans des cas particuliers, mais que c'est n'est pas une solution générale pour mieux décrire les intersections coniques dans les simulations photochimiques basées sur la TD-DFT. La plupart des parties de cette thèse traite d'améliorations algorithmiques, soit pour améliorer l'analyse des résultats de la TD-DFT, soit pour étendre les calculs de TD-DFT à de grandes molécules. L'implémentation de l'analyse automatique des symétries des orbitales moléculaires dans deMon2k est une contribution pour améliorer l'analyse des résultats de la TD-DFT. Cela a aussi servi comme une introduction au projet de programmation majeur. La contribution méthodologique principale dans cette thèse est l'implémentation des équations de Casida dans le code BigDFT fondé sur le formalisme des ondelettes. Cette implémentation a aussi permis une analyse détaillée des arguments positifs et négatifs de l'utilisation de la TD-DFT fondée sur les ondelettes. On montre qu'il est plus facile d'obtenir des orbitales moléculaires précises qu'avec deMon2k. Par contre, la contribution des orbitales inoccupées est plus problématiques qu'avec un code de gaussienne comme deMon2k. Finalement, les équations de base des gradients analytiques des états excités sont dérivées pour la TD-DFT. La thèse se termine avec quelques perspectives de travaux futurs.

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Coppola, Carmen. "Design of novel organic compounds for the development of solar energy conversion devices." Doctoral thesis, Università di Siena, 2022. http://hdl.handle.net/11365/1202089.

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In the last decades, the global perception of the energy crisis has encouraged the research to the development of novel technologies from renewable sources. In particular, great emphasis has been devoted to solar energy conversion devices. While the international photovoltaic market is still dominated by silicon-based solar cells, perovskite solar cells (PSCs), dye-sensitized solar cells (DSSCs) and luminescent solar concentrators (LSCs) are considered as promising alternative technologies in terms of improved manufacturability and for the possibility to reduce the costs and enhance the light trapping of high efficiency silicon-based solar cells. Additionally, in the last years PSCs have become potentially competitive to silicon-based solar cells for their high efficiency, while DSSCs and LSCs have the great advantage to work under diffused light and they can be easily incorporated into the building-integrated photovoltaics (BIPV). Despite the attractive features, these technologies still present some efficiency and instability issues related to their components. For this reason, the design of novel materials for highly performant and stable solar energy conversion devices has become an attractive and challenging issue involving worldwide researchers. In this context, this thesis addresses the design of novel organic compounds to be employed in PSCs, DSSCs and LSCs. In particular, the design of novel organic i) hole transport materials (HTMs) in PSCs, ii) sensitizers in DSSCs and iii) fluorophores in LSCs has been carried out with the aim of contributing to the development of potentially more efficient devices. To this end, state-of-the-art Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TDDFT) methods represent powerful tools for the discovery of promising materials in the solar energy field. Here, they have mainly been applied for the prediction of the most relevant physical-chemical properties of the designed compounds and for the investigation of the structure-property relationships. In such a way it is possible to make an assessment of their suitability to be employed in the aforementioned devices. The outcomes of these studies would provide the fertile ground for future projects that will hopefully contribute to accelerate the research in this field. Indeed, the increased knowledge on the behavior of these materials is the key for boosting the development of solar energy conversion devices in the near future.

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Caserta, Mario. "Dinamica degli stati eccitati della formaldeide tramite teoria del funzionale-densità dipendente dal tempo in tempo reale." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19529/.

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In questo lavoro abbiamo studiato lo stato fondamentale e gli stati eccitati della molecola di formaldeide, che rappresenta il più semplice fra tutti i composti organici contenenti il gruppo carbonile. In particolare abbiamo analizzato l'accoppiamento fra le eccitazioni vibrazionali e le eccitazioni elettroniche. Lo studio è stato realizzato tramite Teoria del Funzionale-Densità (DFT) e Teoria del Funzionale-Densità Dipendente dal Tempo (TDDFT) nei regimi di Risposta Lineare (LR-TDDFT) e di propagazione in Tempo Reale (RT-TDDFT), nell'ambito dell'approssimazione di densità locale (LDA) per il funzionale di scambio e correlazione e dell'approssimazione di campo medio di Ehrenfest per la dinamica semiclassica in tempo reale del sistema accoppiato elettroni-nuclei. Nella prima parte sono state caratterizzate le superfici potenziali dello stato fondamentale e degli stati elettronici eccitati determinate da moti nucleari relativi all'attivazione di un singolo modo normale, nel contesto della dinamica dei nuclei quasi-statica di Born-Oppenheimer. Le superfici potenziali sono state ottenute per lo stato fondamentale tramite DFT e per gli stati eccitati tramite LR-TDDFT. Nella seconda parte del lavoro, tramite un'opportuna scelta di configurazioni iniziali distorte, sono state eseguite delle simulazioni di dinamica molecolare delle eccitazioni elettroniche-nucleari accoppiate. Queste simulazioni sono state svolte nell'ambito della RT-TDDFT/Ehrenfest. Per queste eccitazioni accoppiate sono state analizzate e caratterizzate le oscillazioni nucleari attivate e le configurazioni geometriche molecolari.

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33

Urban, Alexander [Verfasser], and Bernd [Akademischer Betreuer] Meyer. "Environment-dependent crystal-field tight-binding based on density-functional theory / Alexander Urban. Betreuer: Bernd Meyer." Erlangen : Universitätsbibliothek der Universität Erlangen-Nürnberg, 2013. http://d-nb.info/1036774902/34.

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34

Mancini, Lorenzo. "Adiabatic and local approximations for the kohn-sham potential in the hubbard model." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amslaurea.unibo.it/5935/.

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We obtain the exact time-dependent Kohn-Sham potentials Vks for 1D Hubbard chains, driven by a d.c. external field, using the time-dependent electron density and current density obtained from exact many-body time-evolution. The exact Vxc is compared to the adiabatically-exact Vad-xc and the “instantaneous ground state” Vigs-xc. The effectiveness of these two approximations is analyzed. Approximations for the exchange-correlation potential Vxc and its gradient, based on the local density and on the local current density, are also considered and both physical quantities are observed to be far outside the reach of any possible local approximation. Insight into the respective roles of ground-state and excited-state correlation in the time-dependent system, as reflected in the potentials, is provided by the pair correlation function.

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35

Chuang, Yung-ping, and 莊蓉萍. "Time-resolved resonance raman and density functional theory studies ofthe photochemistry of (S)-ketoprofen." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40988156.

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36

Werner, Ute. "Simulation of nonadiabatic dynamics and time-resolved photoelectron spectra in the frame of time-tependent density functional theory." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2011. http://dx.doi.org/10.18452/16351.

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Ziel dieser Arbeit war die Entwicklung einer allgemein anwendbaren Methode für die Simulation von ultraschnellen Prozessen und experimentellen Observablen. Hierfür wurden die Berechnung der elektronischen Struktur mit der zeitabhängigen Dichtefunktionaltheorie (TDDFT) und das Tully-Surface-Hopping-Verfahren für die nichtadiabatische Kerndynamik auf der Basis klassischer Trajektorien miteinander kombiniert. Insbesondere wurde eine Beschreibung der nichtadiabatischen Kopplungen für TDDFT entwickelt. Diese Methode wurde für die Simulation noch komplexerer Systeme durch die Tight-Binding-Näherung für TDDFT erweitert. Da die zeitaufgelöste Photoelektronenspektroskopie (TRPES) ein exzellentes experimentelles Verfahren für die Echtzeitbeobachtung von ultraschnellen Prozessen darstellt, wurde eine TDDFT-basierte Methode für die Simulation von TRPES entwickelt. Der Methode liegt die Idee zu Grunde, das System aus Kation und Photoelektron näherungsweise durch angeregte Zustände des neutralen Moleküls oberhalb der Ionisierungsgrenze zu beschreiben. Um diese Zustände mit TDDFT berechnen zu können wurde eine Beschreibung der Übergangsdipolmomente zwischen angeregten TDDFT-Zuständen entwickelt. Des Weiteren wurden Simulationen im Rahmen des Stieltjes-Imaging-Verfahrens, das eine Möglichkeit der Rekonstruktion des Photoelektronenspektrums aus den spektralen Momenten bietet, durchgeführt. Diese spektralen Momente wurden aus den diskreten TDDFT-Zuständen berechnet. Die breite Anwendbarkeit der entwickelten theoretischen Methoden für die Simulation von komplexen Systemen wurde an der Photoisomerisierung in Benzylidenanilin sowie der ultraschnellen Photodynamik in Furan, Pyrazin und mikrosolvatisiertem Adenin illustriert. Die dargestellten Beispiele demonstrieren, dass die nichtadiabatische Dynamik im Rahmen von TDDFT bzw. TDDFTB sehr gut für die Untersuchung und Interpretation der ultraschnellen photoinduzierten Prozesse in komplexen Molekülen geeignet ist.
The goal of this thesis was the development of a generally applicable theoretical framework for the simulation of ultrafast processes and experimental observables in complex molecular systems. For this purpose, a combination of the time-dependent density functional theory (TDDFT) for the description of the electronic structure with the Tully''s surface hopping procedure for the treatment of nonadiabatic nuclear dynamics based on classical trajectories was employed. In particular, a new approach for the calculation of nonadiabatic couplings within TDDFT was devised. The method was advanced for the description of more complex systems such as chromophores in a solvation shell by employing the tight binding approximation to TDDFT. Since the time-resolved photoelectron spectroscopy (TRPES) represents a powerful experimental technique for real-time observation of ultrafast processes, a TDDFT based approach for the simulation of TRPES was developed. The basic idea is the approximate representation of the combined system of cation and photoelectron by excited states of the neutral species above the ionization threshold. In order to calculate these states with TDDFT, a formulation of the transition dipole moments between excited states within TDDFT was devised. Moreover, simulations employing the Stieltjes imaging (SI) procedure were carried out providing the possibility to reconstruct photoelectron spectra from spectral moments. In this work, the spectral moments were calculated from discrete TDDFT states. The scope of the developed theoretical methods was illustrated on the photoisomerization in benzylideneaniline as well as on the ultrafast photodynamics in furan, pyrazine, and microsolvated adenine. The examples demonstrate that the nonadiabatic dynamics simulations based on TDDFT and TDDFTB are particularly suitable for the investigation and interpretation of ultrafast photoinduced processes in complex molecules.

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37

Karimova, Natalia Vladimirovna. "Theoretical study of the optical properties of the noble metal nanoparticles: CD and MCD spectroscopy." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/38177.

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Doctor of Philosophy
Department of Chemistry
Christine M. Aikens
Gold and silver particles with dimensions less than a nanometer possess unique characteristics and properties that are different from the properties of the bulk. They demonstrate a non–zero HOMO–LUMO gap that can reach up to 3.0 eV. These differences arise from size quantization effects in the metal core due to the small number of atoms. These nanoparticles have attracted great interest for decades both in fundamental and applied research. Small gold clusters protected by various types of ligands are of interest because ligands allow obtaining gold nanoclusters with given sizes, shapes and properties. Three main families of organic ligands are usually used for stabilization of gold nanoclusters: phosphine ligands, thiolate ligands and DNA. Usually, optical properties of these NPs are studied using optical absorption spectroscopy. Unfortunately, sometimes this type of spectrum is poorly resolved and tends to appear very similar for different complexes. In these cases, circular dichroism (CD) and magnetic circular dichroism (MCD) spectroscopy can be applied. However, the interpretation of experimental CD and MCD spectra is a complicated process. In this thesis, theoretically simulated CD and MCD spectra were combined with optical absorption spectra to study optical activity for octa– and nona– and undecanuclear gold clusters protected by mono– and bidentate phosphine ligands. Additionally, optical properties of bare and DNA protected silver NPs were studied. Theoretical CD spectra were examined to learn more about the origin of chirality in chiral organometallic complexes, and to contribute to the understanding of the difference in chiroptical activity of gold clusters stabilized by different phosphine ligands and DNA–stabilized silver clusters. Furthermore, optical properties of the small centered gold clusters Au₈(PPh₃)₈²⁺ and Au₉(PPh₃)₈³⁺ were examined by optical absorption and MCD spectra using TDDFT. Theoretical MCD spectra were also used to identify the plasmonic behavior of silver nanoparticles. These results showed that CD and MCD spectroscopy yield more detailed information about optical properties and electronic structure of the different chemical systems than optical absorption spectroscopy alone. Theoretical simulation of the CD and MCD spectra together with optical absorption spectra can be used to assist in the understanding of empirically measured CD and MCD and provide useful information about optical properties and electronic structure.

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38

Caramella, Lucia. "Theoretical spectroscopy of realistic condensed matter systems." Paris 6, 2009. http://www.theses.fr/2009PA066019.

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Le sujet de cette these porte sur des calculs ab initio de proprietes d'etat fondamental et excite de systemes differents, dans le cadre de la dft et de la tddft. Du cote numerique, nous avons mis en oeuvre une methode originale pour l'evaluation de la polarisabilite dynamique a particules independantes, et generalise un code au spin dans le but d'etudier les proprietes magnetiques de systemes reels. Nous avons etudie des spectres de reflectivite anisotrope et de perte d'energie pour la surface (100) du silicium, propre ou oxydee. La comparaison entre les spectres mesures et simules, nous ont permis d'exclure la reconstruction p(2x1). En suite, nous avons mis en evidence le probleme de la description des excitations des systemes a couche ouverte presente un etude des proprietes optiques d'alliage magnetique interessants pour des applications en spintronique. Nous avons evalue les proprietes d'etat fondamental de ces alliages et la conductivite du fer ccc.

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39

Chuang, Yung-ping. "Time-resolved resonance raman and density functional theory studies of the photochemistry of (S)-ketoprofen." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B40988156.

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40

Zhu, Peizhi, and 朱沛志. "Time-resolved resonance Raman and density functional theory studies ofselected para-phenyl substituted arylnitrenium ions and arylnitrenes." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31246370.

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41

Bergstedt, Mikael. "Theoretical investigation of the first-order hyperpolarizability in the two-photon resonant region." Thesis, Linköping University, The Department of Physics, Chemistry and Biology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-10290.

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Time-dependent density functional theory calculations have been carried out to determine the complex first-order hyperpolarizability in the two-photon resonance region of the molecule IDS-Cab. Calculations show that three strongly absorbing states, in the ultraviolet region, are separated to the extent that no significant interference of the imaginary parts of the tensor elements of the first-order hyper-polarizability occurs. Consequently, and in contrast to experimental findings [27], no reduced imaginary parts of the first-order hyperpolarizability in the two-photon resonant region can be seen.

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42

Guidez, Emilie Brigitte. "Quantum mechanical origin of the plasmonic properties of noble metal nanoparticles." Diss., Kansas State University, 2014. http://hdl.handle.net/2097/17314.

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Doctor of Philosophy
Department of Chemistry
Christine M. Aikens
Small silver and gold clusters (less than 2 nm) display a discrete absorption spectrum characteristic of molecular systems whereas larger particles display a strong, broad absorption band in the visible. The latter feature is due to the surface plasmon resonance, which is commonly explained by the collective dipolar motion of free electrons across the particle, creating charged surface states. The evolution between molecular properties and plasmon is investigated. Time-dependent density functional theory (TDDFT) calculations are performed to study the absorption spectrum of cluster-size silver and gold nanorods. The absorption spectrum of these silver nanorods exhibits high-intensity longitudinal and transverse modes (along the long and short axis of the nanorod respectively), similar to the plasmons observed experimentally for larger nanoparticles. These plasmon modes result from a constructive addition of the dipole moments of nearly degenerate single-particle excitations. The number of single-particle transitions involved increases with increasing system size, due to the growing density of states available. Gold nanorods exhibit a broader absorption spectrum than their silver counterpart due to enhanced relativistic effects, affecting the onset of the longitudinal plasmon mode. The high-energy, high-intensity beta-peak of acenes also results from a constructive addition of single-particle transitions and I show that it can be assigned to a plasmon. I also show that the plasmon modes of both acenes and metallic nanoparticles can be described with a simple configuration interaction (CI) interpretation. The evolution between molecular absorption spectrum and plasmon is also investigated by computing the density of states of spherical thiolate-protected gold clusters using a charge-perturbed particle-in-a-sphere model. The electronic structure obtained with this model gives good qualitative agreement with DFT calculations at a fraction of the cost. The progressive increase of the density of states with particle size observed is in accordance with the appearance of a plasmon peak. The optical properties of nanoparticles can be tuned by varying their composition. Therefore, the optical behavior of the bimetallic Au[subscript](25-n)Ag[subscript]n(SH)[subscript]18[superscript]- cluster for different values of n using TDDFT is analyzed. A large blue shift of the HOMO-LUMO absorption peak is observed with increasing silver content, in accordance with experimental results.

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43

Sheffield, Carolyn Evans. "Time-Resolved Infrared Spectroscopy and Density Functional Theory Study of Weak Interactions of Metal Carbonyls and Organic Solvents." Diss., CLICK HERE for online access, 2010. http://contentdm.lib.byu.edu/ETD/image/etd3389.pdf.

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44

Schelter, Ingo [Verfasser], and Stephan [Akademischer Betreuer] Kümmel. "Excitation dynamics in molecular systems from efficient grid-based real-time density functional theory / Ingo Schelter ; Betreuer: Stephan Kümmel." Bayreuth : Universität Bayreuth, 2017. http://d-nb.info/1131164342/34.

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45

Li, Yunliang, and 李運良. "Time-resolved resonance Raman and density functional theory investigations of selected isopolyhalomethanes, haloalkyl radicals andpolyhalomethane/halogen atom molecular complexes and their reactions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31245717.

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46

李昌運 and Cheong-wan Lee. "Time-resolved resonance Raman and density functional theory investigation of the T1 triplet states and radical cations ofsubstituted biphenyl compounds." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31224623.

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47

Xue, Jiadan, and 薛佳丹. "Time-resolved resonance raman and density functional theory studies ofselected arylnitrenium ions and their reactions with guanosinederivatives and aryl azides." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B41290914.

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48

Ge, Xiaochuan. "Seeing colors with TDDFT: theoretical modeling of the optical properties of natural dyes." Doctoral thesis, SISSA, 2013. http://hdl.handle.net/20.500.11767/4816.

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We have presented a newly developed Davidson-like algorithm to compute selected \textit{interior} eigenstates of the Liouvillian super-operator, and a recently introduced \textit{pseudo-Hermitian} variant of the Liouville-Lanczos approach to time-dependent density-functional theory (TDDFT). The new algorithms have been released as the new version of \texttt{turboTDDFT} in the \textsc{Quantum ESPRESSO} package together with an implementation of hybrid functionals. Our implementation has been thoroughly validated against benchmark calculations performed on a few moleucles using both the original \texttt{turboTDDFT} and \texttt{Gaussian09} code. Then we have applied the new algorithms to carry on a systematic study of anthocyanins' optical properties. We have found that the Oxygen-containing side groups on the phenyl ring of these molecules play important roles to modify their optical absorption spectra, which can be understood by a so-call \textit{double-pole approximation}. We have also applied a recently proposed explicit solvent model to study the solvent effects for these molecules, using a combination of Ab-initio molecular dynamics (AIMD) and TDDFT. We have found that PBE produces too red-shifted spectra, instead B3LYP gives the spectra and the simulated colors in very good agreement with the experiment.

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49

Lee, Cheong-wan. "Time-resolved resonance Raman and density functional theory investigation of the T1 triplet states and radical cations of substituted biphenyl compounds." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22956311.

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50

Oksuz, Nevin. "Quantum-chemical Study Of Geometrical And Electronic Structures Of Aromatic Five-membered Heterocyclic Oligomers In The Ground And Lowest Singlet Excited States." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605397/index.pdf.

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The nature of the ground state and the first (lowest) singlet excited state geometrical conformations and electronic transitions in the aromatic five-membered heterocyclic oligomers &ndash
oligothiophenes (nT), oligofurans (nF), and oligopyrroles (nP)- containing up to six monomer units (total of 18 molecules) were explored using several computational methodologies. Geometry optimizations were carried out at Austin Model 1 (AM1), Restricted Hartree-Fock (RHF/6-31G*), and Density Functional Theory (DFT, B3LYP/6-31G*) levels for the ground-state conformations of these structurally well-defined heterocyclic oligomers. The Configuration Interaction Singles (CIS) method with the 6-31G* basis set was chosen in computation of the optimal geometry of the lowest singlet excited state. Lowest singlet excitation S1ß
S0 energies were calculated using the Zerner&rsquo
s Intermediate Neglect of Differential Overlap for Spectroscopy (ZINDO/S), CIS (CIS/6-31G*), and Time-Dependent DFT (TDDFT/6-31G* and TDDFT/6-31+G*) methods. In computation of the emission S1à
S0 energies, we have employed all methods above except ZINDO/S. In investigation of geometries of the ground and lowest singlet excited state, we compared the bond length alternation (BLA) parameters, Dri in the conjugated backbone of the oligomers. Saturation of the geometrical parameters at the center of oligomers was observed after a certain chain length. Among all methodologies used in computation of excitation (S1ß
S0) and emission (S1à
S0) energies, TDDFT results showed the best agreement with experimental data. Fits of computed and experimental excitation energies to an exponential function using the least squares method enabled us to predict Effective Conjugation Length (ECL) values. We obtained the ECLs of 17 (17), 16 (15), and 14 (13) monomer units for polythiophene (PTh), polyfuran (PFu), and polypyrrole (PPr), which have very good agreement with the results obtained from the fits of experimental data (the values in parentheses).

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Dissertations / Theses on the topic 'Time-dependent density functional theory'

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