Browsing by Author "Mwanga, Stanley F."

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    Molecular and ionic clusters existing in vapor over cesium chloride: Structure and thermodynamic properties.
    (Elsevier, 2016) Pogrebno, Alexander M.; Pogrebnaya, Tatiana P.; Mwanga, Stanley F.
    The properties of neutral molecular Cs2Cl2, Cs3Cl3 and Cs4Cl4 and the positively charged ionic clusters Cs4Cl3+ and Cs5Cl4+ existing in vapor over cesium chloride have been studied. The DFT method with B3LYP5 and B3P86 functionals, and Møller–Plesset perturbation theory of the second and fourth order have been used. The effective core potential with Def2-QZVP basis set for cesium and full electron basis set cc-pVTZ for chlorine were implemented. The geometrical parameters and vibrational frequencies of species have been determined. Isomers of two kinds have been revealed for Cs3Cl3 and Cs4Cl3+ species, and their relative concentrations in vapor were evaluated. The dissociation reactions of the clusters with elimination of CsCl molecule were examined and enthalpies of reactions and enthalpies of formation of the species have been determined.
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    Theoretical study of cluster ions existing in vapours over cesium bromide and iodide
    (SCIENCEDOMAIN international, 2015) Mwanga, Stanley F.; Pogrebnaya, Tatiana P.; Pogrebnoi, Alexander M.
    The properties of ions Cs2X+, Cs3X2+, CsX2−, and Cs2X3− (X = Br or I) have been studied using the density functional theory and Möller–Plesset perturbation theory of the 2nd and 4th order. For all species the equilibrium geometrical configurations and vibration frequencies were determined. Different isomers of pentaatomic ions were found to exist: the linear (D∞h), V-shaped (C2v), kiteshaped (C2v) and bipyramidal (D3h). The relative abundances of isomers were calculated for temperatures between 700 K and 1600 K. It was found that at about 800 K, the amount of different isomers was comparable for Cs3Br2+, Cs3I2+ and Cs2I3− ions, while for Cs2Br3− the linear isomer was proved to be predominant. The enthalpies of dissociation reactions with elimination of CsX molecules and the enthalpies of formation of ions were determined.