Browsing by Author "Graves, Richard Marshall"

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    A comprehensive ab initio study of gallium and arsenic containing molecules
    (1992) Graves, Richard Marshall; Scuseria, Gustavo E.
    Theoretical calculations for the ground states of arsine (AsH$\sb3$), trimethylgallium (TMG) (Ga(CH$\sb3$)$\sb3$), the arsine$\cdot$TMG adduct, gallane (GaH$\sb3$), the gallane$\cdot$arsine adduct, small Ga$\sb{x}$As$\sb{y}$ clusters (x = y; x = 2-4), and small gallium hydrides are carried out at the self consistent field (SCF) Hartree-Fock level of theory, using analytic energy gradients for rapid geometry optimization. In addition, the SCF results are compared with theoretical predictions obtained at the coupled cluster level of theory including all single and double excitations, (CCSD). The precursors to the formation of GaAs, arsine and TMG, were determined to be of C$\sb{3v}$ and C$\sb3$ symmetries, respectively, while gallane was found to be D$\sb{3h}$ The equilibrium structures for Ga$\sb2$As$\sb2$, Ga$\sb3$As$\sb3$, and Ga$\sb4$As$\sb4$ are found to be of D$\sb{2h}$, C$\sb1$, and C$\sb{i}$ symmetry, respectively. The adduct binding energies and vibrational frequencies (SCF) are also obtained resulting in two stable bonded adduct species, arsine$\cdot$TMG of symmetry point group C$\sb3$ and arsine$\cdot$gallane of C$\sb{3v}$ symmetry. Finally, our theoretical predictions support a slightly exothermic gas-phase reaction yielding GaAs through a TMG$\cdot$AsH$\sb3$ adduct which is formed without an activation barrier.