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Thermodynamic Properties of Arsenic Compounds and the Heat of Formation of the As Atom from High Level Electronic Structure Calculations

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journal contribution
posted on 29.12.2011, 00:00 by David Feller, Monica Vasiliu, Daniel J. Grant, David A. Dixon
Structures, vibrational frequencies, atomization energies at 0 K, and heats of formation at 0 and 298 K are predicted for the compounds As2, AsH, AsH2, AsH3, AsF, AsF2, and AsF3 from frozen core coupled cluster theory calculations performed with large correlation consistent basis sets, up through augmented sextuple zeta quality. The coupled cluster calculations involved up through quadruple excitations. For As2 and the hydrides, it was also possible to examine the impact of full configuration interaction on some of the properties. In addition, adjustments were incorporated to account for extrapolation to the frozen core complete basis set limit, core/valence correlation, scalar relativistic effects, the diagonal Born–Oppenheimer correction, and atomic spin orbit corrections. Based on our best theoretical D0(As2) and the experimental heat of formation of As2, we propose a revised 0 K arsenic atomic heat of formation of 68.86 ± 0.8 kcal/mol. While generally good agreement was found between theory and experiment, the heat of formation of AsF3 was an exception. Our best estimate is more than 7 kcal/mol more negative than the single available experimental value, which argues for a re-examination of that measurement.

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