Chemistry & Biochemistry Theses and Dissertations

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Browsing Chemistry & Biochemistry Theses and Dissertations by Subject "ab initio"

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    A PHYSICAL CHEMIST'S GUIDE TO APPLIED COMPUTATIONAL CHEMISTRY: PRACTICAL CALCULATION OF POLYPROTIC ACID PKA VALUES, MERCURY HALIDES, THIOLS, AND METHYLMERCURY ANALOGUES' STABILITIES AND STRUCTURES, AND RAMAN SPECTRA OF MYO-INOSITOL HEXAKIS PHOSPHATE.
    (2010) Zimmermann, Merle; Tossell, John A; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    In this thesis, we present both ab-initio investigation of the series of compounds HgClxy and the charges of each system running x=(0,1,2,3,4) and y=(+2,+1,0,-1,-2). We investigate the energies of formation using Gaussian 03 (G03), a quantum chemistry package. In our calculations, HgCl3-1 was most stable in the gas phase, and HgCl20 the most stable in the polarizable continuum model water-solvated phase. The addition of a solvent layer of H2O molecules did not significantly affect the results. DFT calculations on the series running between HgCl+, through HgCl20, and HgCl3-1 compounds done with the Amsterdam Density Functional (ADF) program from Scientific Computing and Modeling (SCM) yielded absolute Hg NMR shieldings with a Δ of approximately -1000 ppm for each additional atom of Chlorine bonding to the Mercury for the first two additions. We also investigate H3PO4, H3AsO4, and the HClOx acid series with x=(1,2,3,4). We have succeeded in determining pKas with theoretical quality results within 2 kcal/mol of experimental measurement for the majority of the systems examined by use of a discovered linear correlation between experimental and calculated pKa values. Finally, we present our contribution to a joint project involving myo-inositol hexakis phosphate with an experimental group, confirming the observed experimental trends seen in the Raman spectra.