Accurate prediction of thermodynamic properties of alkyl peroxides by combining density functional theory calculation with least‐square calibration

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 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.

The Corrected Values of ΔrHo(CaHbOd, a≤16) of Atomization of the Aromatic Compounds and Their Uncertainties Determined Using Several Quantum Mechanical Approaches

“…The values of SE Y and SE YE <3 kJ/mol, determined in the present work for the considered PAH are also consistent with the accuracy, reported for others organic compounds [20–24] . However, in many of these cases, the not straightforward three parameters scaling dependencies are used for determination of the standard enthalpies of formation of the smaller and not aromatic compounds.…”

Importance of Spin Channels from Radical–Radical Reactions in Hydrogen–Oxygen Combustion Mechanisms at High Temperatures

“…Table S4 presents L-J parameters . The rigid-rotor harmonic oscillator (RRHO) model was used to calculate the density of states and partition functions for the local minima and the number of states for transition states. The contributions of low-frequency torsional motions in partition function calculations were estimated by the one-dimensional hindered internal rotor method .…”