THERMOCHEMICAL PROPERTIES FOR HYDROGENATED AND OXY-HYDROGENATED ALUMINUM SPECIES

摘要

The availability of accurate thermochemical data such as heats of formation, heat capacities, and entropies for Al_xH_y, Al_xO_y, and Al_xO_yH_z species in the gas phase, is essential in many applications. In this study, we predict geometries and enthalpy of formation, △_∫ H_(298)~0, of a large set of aluminum species (reactants, intermediates, radicals, and products) describing the Al_xO_yH_z system. Three calculation methods with proven accuracy, Density Functional theory (DFT) at (B3LYP/6-311G(d,p)), G3MP2, and CBS-QB3, are used for each species. The ab initio and Density Functional calculations are combined with isodesmic reaction analysis, whenever possible, in order to improve the accuracy of the enthalpy values. Estimation and analysis of bond energies in AlH_x and AlH_xO_y are reported. Entropies, S_(∫298)~0 and heat capacities, G_(pf298)(T) were calculated using DFT calculation results.