Atom-centered potentials for describing London dispersion forces in density functional theoryReport as inadecuate

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Lausanne: EPFL, 2008

The Kohn-Sham formulation of density functional theory (DFT) has posed itself as one of the most popular and versatile methods for condensed phase studies owing to its reasonable accuracy and affordable computational cost. DFT, in principle, yields exact ground state energy, including dispersion forces that are of primordial importance in chemical and biological systems. Yet with many exchange-correlation functionals in practical use such as the local density approximation or generalized gradient approximations, DFT either provides sporadic results or fails completely to account for these forces. In consequence, various methods offering remedy for this shortcoming have been proposed in this active field of research. In particular, dispersion-corrected atom-centered potentials (DCACPs) serve as a robust and efficient way to include these weak forces in a fully self-consistent manner within current DFT frameworks. The aim of this thesis is twofold: first, to improve the predictive power and the understanding of the DCACP concept; second, applying DCACPs to systems of increasing complexity starting with dimers, continuing through larger clusters and ending with the condensed phase. The success of the second aim not only justifies the use of DCACPs but more importantly, provides insights to the role dispersion forces play in the systems investigated. We first draw on the atoms-in-molecules theory and a multi-center density expansion to justify the form and universality of DCACPs. A library of DCACPs calibrated with an improved penalty functional against high-level ab initio references is presented. With the library in hand, we extend our studies to systems of biological significance, mainly constituents of proteins and DNA; polycyclic aromatic molecules intercalated in between segments of DNA are the center of focus. The application of DCACPs is then furthered to the condensed phase and the importance of van der Waals interactions in liquid water is investigated.

Keywords: amino acids ; density functional theory ; dispersion-corrected atom-centered potentials ; dispersion forces ; interaction energy ; liquid water ; nucleic acids ; acides aminés ; acides nucléiques ; eau liquide ; énergie d'interaction ; forces de dispersion ; théorie de la fonctionnelle de la densité ; potentiels centrés sur les atomes et corrigés pour la dispersion Thèse École polytechnique fédérale de Lausanne EPFL, n° 4058 (2008)Programme doctoral Chimie et Génie chimiqueSection de chimie et génie chimiqueFaculté des sciences de baseInstitut des sciences et ingénierie chimiquesLaboratoire de chimie et biochimie computationnellesJury: Matteo Dal Peraro, Jürg Hutter, Michiel Sprik Public defense: 2008-4-4 Reference doi:10.5075/epfl-thesis-4058Print copy in library catalog

Author: Lin, I-ChunAdvisor: Röthlisberger, Ursula



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