

@mastersthesis {6945,
	title = {Ab initio electronic structure methods for intermolecular interactions},
	year = {2007},
	note = {3275468},
	school = {University of California, Berkeley},
	type = {phdPh.{D}.},
	address = {Ann Arbor},
	abstract = {Intermolecular interactions determine physical and chemical properties of a broad class of important systems such as liquids, solutions and molecular solids. First principles electronic structure methods are playing an important role in the study of weakly bonded ensembles of molecules. However, the applicability of ab initio methods is severely limited by poor scaling. The diagonalization of the effective Hamiltonian matrix, which scales cubically with the system size, becomes the bottleneck for calculations for large systems. In the first part of this work, we propose an efficient method for removing the self-consistent field (SCF) diagonalization bottleneck for systems of weakly interacting components. The method is based on the equations of the locally-projected SCF which utilize nonorthogonal absolutely localized molecular orbitals expanded in local subsets of the atomic basis set. A generalization of direct inversion in the iterative subspace for nonorthogonal molecular orbitals is formulated to increase the rate of convergence of the locally-projected SCF equations and a perturbative correction is developed to improve the accuracy of the locally-projected SCF method. Next, we proceed to show how absolutely localized molecular orbitals can be used to formulate an energy decomposition analysis (EDA) method that isolates physically relevant components of the total intermolecular interaction energies such as the contribution from interacting frozen monomer densities, the energy lowering due to polarization of the densities and the further energy lowering due to charge transfer effects. The newly proposed EDA method is used to understand the fundamental aspects of intermolecular interactions such as the degree of covalency in the hydrogen bonding in water and the contributions of forward and back-donation in synergic bonding in metal complexes. Additionally, it is demonstrated that this method can be used to identify the factors controlling the interaction of molecular hydrogen with open metal centers in potential hydrogen storage materials and the interaction of methane with rhenium complexes. Finally, we applied ab initio electronic structure methods to study the mechanism of free radical generation from molecular hydrogen peroxide in the catalytic system vanadate/pyrazine-2-carboxylic acid and the origin of a strong solvent effect on the extent of iron(III) [tetrakis-(pentafluorophenyl)]-porphyrin chloride dissociation in acetonitrile-methanol solutions.},
	keywords = {0494:Chemistry, Chemistry, Energy decomposition, Free radicals, Pure sciences, Self-consistent fields},
	url = {http://search.proquest.com/docview/304900740?accountid=14270},
	author = {Khaliullin, Rustam Zakar evich}
}
