@prefix dcat: . @prefix dct: . @prefix foaf: . @prefix vcard: . @prefix xsd: . a dcat:Dataset ; dct:description """ The interaction of light with matter is a well-established domain of physical science. For a chemical physicist, this interaction may be used as a probe (spectroscopy) or to induce chemical reactions (photo- chemistry.) Photochemical reaction mechanisms are difficult to study experimentally and even the most sophisticated modern femtosecond spectroscopic studies can benefit enormously from the light of theoret- ical simulations. Spectroscopic assignments often also require theoreti- cal calculations. Theoretical methods for describing photoprocesses have been developed based upon wave-function theory and show remarkable success when going to sophisticated higher-order approxi- mations. However such approaches are typically limited to small or at best medium-sized molecules. Fortunately time-dependent density- functional theory (TD-DFT) has emerged as a computationally-simpler method which can be applied to larger molecules with an accuracy which is often, but not always, similar to high-quality wave-function calculations. Part of this thesis concerns overcoming difficulties in- volving the approximate functionals used in present-day TD-DFT. In particular, we have examined the quality of conical intersections when the Ziegler-Wang noncollinear spin-flip approach is used and have shown that the spin-flip approach has merit as a particular solution in particular cases but is not a general solution to improving the de- scription of conical intersections in photochemical simulations based upon TD-DFT. Most of this thesis concerns algorithmic improvements aimed at either improving the analysis of TD-DFT results or extending practical TD-DFT calculations to larger molecules. The implementa- tion of automatic molecular orbital symmetry analysis in deMon2k is one contribution to improving the analysis of TD-DFT results. It also served as an introduction to a major programming project. The major methodological contribution in this thesis is the implementation of Casida's equations in the wavelet-based code BigDFT and the subse- quent analysis of the pros and cons of wavelet-based TD-DFT where it is shown that accurate molecular orbitals are more easily obtained in BigDFT than with deMon2k but that handling the contribution of unoccupied orbitals in wavelet-based TD-DFT is potentially more problematic than it is in a gaussian-based TD-DFT code such as de- Mon2k. Finally the basic equations for TD-DFT excited state gradients are derived. The thesis concludes with some perspectives about future work. """ ; dct:identifier "NNT: 2012GRENV002" ; dct:issued "2026-05-23T16:30:10.069679"^^xsd:dateTime ; dct:language "fr" ; dct:modified "2026-05-23T16:30:10.069685"^^xsd:dateTime ; dct:publisher ; dct:title "Implementation, Testing, and Application of Time-Dependent Density-Functional Theory Algorithms for Gaussian- and Wavelet-based Programs" ; dcat:contactPoint [ a vcard:Organization ; vcard:fn "CCSD" ] ; dcat:distribution ; dcat:keyword "density-functional-theory", "gaussian-functions", "gaussiennes", "infoeu-reposemanticsdoctoralthesis", "la-theorie-fonctionnelle-de-densite-dependant-du-temps", "ondelettes", "sdvsalife-sciences-q-bioagricultural-sciences", "theses", "time-dependent-density-functional-theory", "wavelets" ; dcat:landingPage . a dcat:Distribution ; dct:format "HTML" ; dct:issued "2026-05-23T16:30:10.111098"^^xsd:dateTime ; dct:modified "2026-05-23T16:30:10.041601"^^xsd:dateTime ; dct:title "Implementation, Testing, and Application of Time-Dependent Density-Functional Theory Algorithms for Gaussian- and Wavelet-based Programs" ; dcat:accessURL . a foaf:Agent ; foaf:name "test_moissonnage_selune" . a foaf:Document .