Accurate prediction of thermodynamic properties of alkyl peroxides by combining density functional theory calculation with least-square calibration.
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 Delta(f)H(298)(o) of alkyl peroxides. By this method, a raw Delta(f)H(298)(o) value was calculated from the optimized geometry and vibration frequencies at B3LYP/6-31G(d,p) level and then an accurate Delta(f)H(298)(o) 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 Delta(f)H(298)(o) 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.
Liu
Cun-Xi
CX
College of Chemistry, Sichuan University, Chengdu 610065, People's Republic of China.
Li
Ze-Rong
ZR
Zhou
Chong-Wen
CW
Li
Xiang-Yuan
XY
D002138:Calibration; D003198:Computer Simulation; D016018:Least-Squares Analysis; D008956:Models, Chemical; D010545:Peroxides / Q000737:chemistry*; D013816:Thermodynamics
D010545:Peroxides