The heat of atomization of sulfur trioxide, SO${}_3$ - a benchmark for computational thermochemistry

Abstract

Calibration ab initio (direct coupled cluster) calculations including basis set extrapolation, relativistic effects, inner-shell correlation, and an anharmonic zero-point energy, predict the total atomization energy at 0 K of SO${}_3$ to be 335.96 (observed 335.92$\pm$0.19) kcal/mol. Inner polarization functions make very large (40 kcal/mol with $spd$, 10 kcal/mol with $spdfg$ basis sets) contributions to the SCF part of the binding energy. The molecule presents an unusual hurdle for less computationally intensive theoretical thermochemistry methods and is proposed as a benchmark for them. A slight modification of Weizmann-1 (W1) theory is proposed that appears to significantly improve performance for second-row compounds.

Chem. Phys. Lett., in press

References in corpus (3)

• Towards standard methods for benchmark quality ab initio thermochemistry --- W1 and W2 theory
• A fully ab initio quartic force field of spectroscopic quality for SO_3
• A definitive heat of vaporization of silicon through benchmark ab initio calculations on SiF_4

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