| Abstrakt: |
The thorough complete basis set, Gaussian ab initio, hybrid, and gradient-corrected density functional methods of computational studies were performed on the CH + NO reaction with the target being to determine the stable adduct intermediates, their enthalpies of formation, and the enthalpies for various branching pathways. This reaction has enormous importance in both combustion and atmospheric chemistry, and it is very important to have its accurate energy profile. The computed values are compared with the experimental values, and in almost all cases, the currently used energies should be corrected. Considering the accuracy of these high level ab initio methods, it is believed that the listed values in this paper are the most accurate up to date. The complete basis set computed values are the most accurate and are, for the enthalpy of formation at 0 K for HNCO and NCO, 39.2 and 28.3 kcal/mol, respectively. The H−N and N−C bond dissociation energies for HNCO are 109.6 and 87.4 kcal/mol. The suggested CBSQ enthalpies at 298 K for the CH + NO branching reaction are −3.47 eV for H (2S) + NCO (X2Π, Ã2Σ+), −4.42 eV CO (X1Σ+) + NH (X3Σ-); −3.03 eV O (3P,1D) + HCN (X1Σ+), −1.97 eV OH (X2Π) + CN (X2Σ+, A2Πi), −1.69 eV N (4S) + HCO (X2A, Ã2A ), −0.76 eV H (2S) + CNO (X2Π), and −1.01 eV H (2S) + N (2S) + CO (X1Σ+). |
