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Accurate prediction of thermodynamic properties of alkyl peroxides by combining density functional theory calculation with least‐square calibration
Author(s) -
Liu CunXi,
Li ZeRong,
Zhou ChongWen,
Li XiangYuan
Publication year - 2009
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.21122
Subject(s) - chemistry , calibration , thermodynamics , alkyl , standard enthalpy of formation , correlation coefficient , mean squared error , square (algebra) , mathematics , physics , statistics , organic chemistry , geometry
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 o 298of alkyl peroxides. By this method, a raw Δ f H o 298value was calculated from the optimized geometry and vibration frequencies at B3LYP/6‐31G(d,p) level and then an accurate Δ f H o 298value 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 o 298values 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