Accurate prediction of thermodynamic properties of alkyl peroxides by combining density functional theory calculation with least-square calibration
✍ Scribed by Cun-Xi Liu; Ze-Rong Li; Chong-Wen Zhou; Xiang-Yuan Li
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 117 KB
- Volume
- 30
- Category
- Article
- ISSN
- 0192-8651
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✦ Synopsis
Abstract
Owing to the significance in kinetic modeling of the oxidation and combustion mechanisms of hydrocarbons, a fast and relatively accurate method was developed for the prediction of Δ~f~H of alkyl peroxides. By this method, a raw Δ~f~H value was calculated from the optimized geometry and vibration frequencies at B3LYP/6‐31G(d,p) level and then an accurate Δ~f~H value was obtained by a least‐square procedure. The least‐square procedure is a six‐parameter linear equation and is validated by a leave‐one out technique, giving a cross‐validation squared correlation coefficient q^2^ of 0.97 and a squared correlation coefficient of 0.98 for the final model. Calculated results demonstrated that the least‐square calibration leads to a remarkable reduction of error and to the accurate Δ~f~H values within the chemical accuracy of 8 kJ mol^−1^ except (CH~3~)~2~CHCH~2~CH~2~CH~2~OOH which has an error of 8.69 kJ mol^−1^. Comparison of the results by CBS‐Q, CBS‐QB3, G2, and G3 revealed that B3LYP/6‐31G(d,p) in combination with a least‐square calibration is reliable in the accurate prediction of the standard enthalpies of formation for alkyl peroxides. Standard entropies at 298 K and heat capacities in the temperature range of 300–1500 K for alkyl peroxides were also calculated using the rigid rotor‐harmonic oscillator approximation. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009